Re: Subjects as Literals, [was Re: The Ordered List Ontology]
I use RDF like a next-generation relational database and think that RDF could be sold to many people this way (there is possibly are larger audience for this than for ontologies, reasoning, etc.). Especially considering how No-SQL is currently taking off. This part needs some love and seems to suffer from the almost exclusive focus on semantics. Fair enough. I guess Im not sure how this next-generation-RDB usage fits with the RDF semantics, but I'd be interested in pursuing this further. Does this RDF/RDB++ vision provide any guidance towards what RDF is supposed to, like, mean? Pointers? Does it have to mean anything? I’ve always found tuple calculus and relational algebra quite intuitive, but as far as I remember, it is very light on semantics, everything is just data. URIs as symbols are useful, but I would not know how to express the concepts they represent formally. What else is needed? A simple schema language, which should probably assume a closed world and unique names (unless specified otherwise). I’m surprised how something that is trivial (and common!) for relational databases is very hard for SPARQL (for example, letting SPARQL return a table where each row is a resource [1]). Additionally, it would be useful if SPARQL allowed one to do backward-chaining via rules (some RIF implementations seem to do this). I can only come up with a few use-cases (sub-properties, transitive properties), but those would definitely help. [1] http://www.w3.org/2009/12/rdf-ws/papers/ws17 There might not be anything in it, scientifically, but it would help to sell RDF to a community that is largely orthogonal to the one that is after RDF + semantics. -- Dr. Axel Rauschmayer axel.rauschma...@ifi.lmu.de http://hypergraphs.de/ ### Hyena: connected information manager, free at hypergraphs.de/hyena/
RE: Subjects as Literals, [was Re: The Ordered List Ontology]
On Behalf Of Nathan wrote on Friday, July 02: Pat Hayes wrote: On Jul 1, 2010, at 11:18 AM, Yves Raimond wrote: A literal may be the object of an RDF statement, but not the subject or the predicate. Just to clarify, this is a purely syntactic restriction. Allowing literals in subject position would require **no change at all** to the RDF semantics. (The non-normative inference rules for RDF and RDFS and D-entailment given in the semantics document would need revision, but they would then be simplified.) I have to wonder then, what can one all place in the s,p,o slots without changing the RDF semantics? literal and bnode predicates for instance? Short answer: you can put URIs, literals and bNodes in all three positions of a triple, without needing to touch the current RDF semantics spec. Longer answer: The syntactic restrictions of RDF (no literal subjects, no literal or bnode predicates) are not checked by the semantic conditions of the RDF semantics. Every node in a triple is (in a first step) simply related to some resource in the interpreted universe. For URI nodes this is probably clear, but even literals are meant to represent resources: all datavalues are treated as resources in RDF! bNodes are a bit different, since they do not stand directly for a specific resource, but indicate that some resource /exists/. But, in the end, all you receive from the interpretation of all the nodes occurring in an RDF triple is essentially a binary relationships between two resources. And the rest of the semantics specification of RDF(S), and even of OWL Full, works exclusively on these kinds of sets of binary relationships, below the syntax surface, so to speak. So the whole stack of RDF-based semantics is ready to be used with generalized RDF out of the box -- just waiting for the RDF syntax to give up its restrictiveness. :-) As a special note: Even bNode predicates, and even literal predicates are allowed in the RDF semantics and make sense (in a technical sense, at least), because: (a) Properties are also treated as regular resources by the RDF semantics. They have some binary relation attached to them (in order to allow to use them to relate two resources), but you can still treat them like any other resource, e.g. relate themselves to another resource by some other property). (b) Literals stand for data value resources, and nothing stops a data value resource from being used as a predicate resource. (I leave it to the philosophers here in the list to debate whether this is good use or bad use in practice.) variables or formulae as in n3? For formulae: Certainly no, since formulae are normally not interpreted to denote resources, but are assertions being interpreted by a truth value. For variables: Firstly, /existentially/ quantified variables are already treated, since they are represented by bNodes. Remains /universally/ quantified variables, as they exist in N3. Supporting them would definitely need /some/ extension of the RDF semantics, since it has at least to be said how such variables are interpreted (this is only said for URIs, plain and typed literals, and for bNodes so far in the spec, see Sections 1.4 and 1.5 of the RDF Semantics [1]). I just cannot tell how much extension would be required without more deeply thinking about it. So this question keeps open from my side at the moment. Maybe Pat has an answer? read as: if a new serialization/syntax was defined for RDF what are the limitations for the values of node/object and relationship specified by the RDF Semantics? Best, Nathan ps: apologies if this is a dumb question, I fear i'd still be hear next year trying to answer it myself though ;) Not dump at all. Technically pretty demanding, in fact. Cheers, Michael [1] http://www.w3.org/TR/rdf-mt/ -- Dipl.-Inform. Michael Schneider Research Scientist, Information Process Engineering (IPE) Tel : +49-721-9654-726 Fax : +49-721-9654-727 Email: michael.schnei...@fzi.de WWW : http://www.fzi.de/michael.schneider === FZI Forschungszentrum Informatik an der Universität Karlsruhe Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe Tel.: +49-721-9654-0, Fax: +49-721-9654-959 Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael Flor, Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus ===
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
[cc's trimmed] I'm with Jeremy here, the problem's economic not technical. If we could introduce subjects-as-literals in a way that: (a) doesn't invalidate any existing RDF, and (b) doesn't permit the generation of RDF/XML that existing applications cannot parse, then I think there's a possible way forward. #g -- BTW, which list is the most appropriate for this discussion? I seem to be getting 4 copies of some messages! Jeremy Carroll wrote: Jiří Procházka wrote: I wonder, when using owl:sameAs or related, to name literals to be able to say other useful thing about them in normal triples (datatype, language, etc) does it break OWL DL yes it does (or any other formalism which is base of some ontology extending RDF semantics)? Not OWL full Or would it if rdf:sameAs was introduced? It would still break OWL DL Best, Jiri OWL DL is orthogonal to this issue. The OWL DLers already prohibit certain RDF - specifically the workaround for not having literal as subjects. So they are neutral. I reiterate that I agree whole-heartedly with the technical arguments for making this change; however the economic case is missing. Jeremy
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Hello Ivan! On Fri, Jul 2, 2010 at 5:50 AM, Ivan Mikhailov imikhai...@openlinksw.com wrote: Hello Yves, It's a virtuoso function surfaced as a predicate. magic predicate was an initial moniker used at creation time. bif:contains doesn't exist in pure triple form etc.. Why couldn't it? For example, you may want to express exactly what triple lead you to give a particular result, and within that scope you may end up having to write: Brickley bif:contains ckley in RDF. Forbidding literals as subjects makes this statement impossible to express, however that's a very sensible thing you may want to express. There are also lots of literal search examples that comes to mind: Acton str:double_metaphone AKTN . Smith str:soundex S530 . Yes, SPARQL permits literals in subject position, and we use that for dirty hacks. That does not mean that raw data should permit the same. SPARQL (and especially our SPARQL/BI) uses many different things in subject position, e.g., variables (and expressions, up to subqueries) that's not an excuse to allow the same in raw data. First: this is *not* a dirty hack. Brickley bif:contains ckley is a perfectly valid thing to say. I don't even say about technical price of the extension for both developers (extra work) and each user of any big RDF storage (extra hardware). I simply don't see a reason, because literals are simply I am not arguing for each vendor to implement that. I am arguing for removing this arbitrary limitation from the RDF spec. Also marked as an issue since 2000: http://www.w3.org/2000/03/rdf-tracking/#rdfms-literalsubjects That aside, I don't see your point about extra hardware. There is, in my experience, no substantial difference between storing #me foaf:name Ivan and Ivan :name_of #me. _not_enough_unique_ to interlink data. There are. Their value is their identity. They are *perfectly* unique. cat is uniquely identifying the string made of c, a and t. From your previous email, I suppose you're concerned about rounding for floats and doubles, is that it? If so, whatever you write as their rounded value is their identity (and we can't write Pi^^xsd:real afaik :) ). [ ] str:double_metaphone_word Acton ; str:double_metaphone AKTN . and [ ] str:soundex_word Smith ; str:soundex S530 . I agree this is another way to model it, and Jeremy suggested it as well. But it creates a level of indirection and, from a modeling point of view, does look very weird. If you were to extend that model to, say, 1 list:in (1 2 3), that would look very nasty... Best, y are at least protected from collisions and allow more properties to be added in a safe way. Best Regards, Ivan Mikhailov OpenLink Software http://virtuoso.openlinksw.com
RE: Subjects as Literals, [was Re: The Ordered List Ontology]
Pat Hayes wrote: Just to clarify, this is a purely syntactic restriction. Allowing literals in subject position would require **no change at all** to the RDF semantics. Indeed. And this is probably one of the reasons why several RDF-related standards have already adopted literal subjects. Some examples: * For the OWL 2 RDF-Based Semantics, being an extension of the RDF Semantics, it has been explicitly allowed (in the MAY sense) to apply it to generalized RDF, where literals and bNodes may occur in any position of a triple: http://www.w3.org/TR/owl2-rdf-based-semantics/#topic-ont-generalrdf (However, OWL 2 Full is still defined to be the language that consists of the RDF-Based Semantics and the official RDF Syntax, i.e. where subjects are not allowed to be literals.) * The OWL 2 RL/RDF Ruleset also allows for generalized RDF, see the second paragraph of http://www.w3.org/2007/OWL/wiki/Profiles#Reasoning_in_OWL_2_RL_and_RDF_Grap hs_using_Rules * The RIF RDF and OWL Compatibility specification (just became a W3C Recommendation) also uses generalized RDF, see the note at http://www.w3.org/TR/2010/REC-rif-rdf-owl-20100622/#note-generalized-rdf-gr aphs and the definitions at http://www.w3.org/TR/2010/REC-rif-rdf-owl-20100622/#RDF_Vocabularies_and_Gr aphs * SPARQL 1.1 (still work in progress) allows literal subjects in Triple Patterns: http://www.w3.org/TR/sparql11-query/#defn_TriplePattern I could imagine that this list of important technologies allowing for literal subjects will grow over time, and maybe there even exist some more today that I missed. If RDF2 would also adopt generalized RDF, all these RDF-dependent standards could then be updated by dropping all these MAYs and similar statements. Michael -- Dipl.-Inform. Michael Schneider Research Scientist, Information Process Engineering (IPE) Tel : +49-721-9654-726 Fax : +49-721-9654-727 Email: michael.schnei...@fzi.de WWW : http://www.fzi.de/michael.schneider === FZI Forschungszentrum Informatik an der Universität Karlsruhe Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe Tel.: +49-721-9654-0, Fax: +49-721-9654-959 Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael Flor, Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus ===
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Yves, On Fri, Jul 2, 2010 at 10:15 AM, Yves Raimond yves.raim...@gmail.com wrote: First: this is *not* a dirty hack. Brickley bif:contains ckley is a perfectly valid thing to say. You could, today, use data: URIs to represent literals with no change to any RDF system. Ian
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Fri, 2010-07-02 at 08:50 +0100, Graham Klyne wrote: [cc's trimmed] I'm with Jeremy here, the problem's economic not technical. If we could introduce subjects-as-literals in a way that: (a) doesn't invalidate any existing RDF, and (b) doesn't permit the generation of RDF/XML that existing applications cannot parse, then I think there's a possible way forward. Yes, there's such a way, more over, it will be just a small subset of a richer language that is widely used already, so it will require very little coding. When there's a need in SPARQL-like extensions, like subjects-as-literals, there's a straightforward way of serializing data as SPARQL fragments. Note that in this way not only subjects-as-literals are available, but even SPARQL 1.1 features like path expressions or for each X expressed as ?X in an appropriate place of an appropriate BGP. Best Regards, Ivan Mikhailov, OpenLink Software http://virtuoso.openlinksw.com
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Hi Yves, [trimmed cc list] On 2 Jul 2010, at 11:15, Yves Raimond wrote: I am not arguing for each vendor to implement that. I am arguing for removing this arbitrary limitation from the RDF spec. Also marked as an issue since 2000: http://www.w3.org/2000/03/rdf-tracking/#rdfms-literalsubjects The demand that W3C modify the specs to allow literals as subjects should be rejected on a simple principle: Those who demand that change, including yourself, have failed to put their money where their mouth is. Where is the alternative specification that documents the syntactic and semantic extension? Where are the proposed RDF/XML++ and RDFa++ that support literals as subjects? Where are the patches to Jena, Sesame, Redland and ARC2 that support these changes? The restriction seems to bother some people enough that they write noisy emails, but it apparently doesn't bother them enough to actually do anything about it. W3C's job should be to broker compromises between non-interoperable approaches by different vendors, and to foster adoption by putting its stamp of approval on already widely deployed technologies developed by the community. You know, the kind of stuff that actually came out near the top of the RDF Next Steps work item poll [1]: named graphs, Turtle, RDF/JSON. Someone mentioned HTML 3.2 in this thread. Let me mention the ill- fated XHTML 2.0. A group of markup purists who were more interested in polishing the arcane details of the language, rather than meeting the interests of the heaviest users and the vendors. They did an enormous disservice to W3C and the web. The users and vendors turned their back on W3C, started their own effort, and W3C ultimately had to abandon XHTML 2.0 or risk to become irrelevant to the future of HTML. Literals as subjects feels very much like an XHTML 2.0 kind of feature to me. Or, coming at it from a completely different direction: I have yet to meet a person (except Nathan perhaps) who says, Yeah that RDF stuff, I had a look at it but then saw that it does not support literals as subjects, so I gave up on it. Best, Richard [1] http://www.w3.org/2010/06/rdf-work-items/table That aside, I don't see your point about extra hardware. There is, in my experience, no substantial difference between storing #me foaf:name Ivan and Ivan :name_of #me. _not_enough_unique_ to interlink data. There are. Their value is their identity. They are *perfectly* unique. cat is uniquely identifying the string made of c, a and t. From your previous email, I suppose you're concerned about rounding for floats and doubles, is that it? If so, whatever you write as their rounded value is their identity (and we can't write Pi^^xsd:real afaik :) ). [ ] str:double_metaphone_word Acton ; str:double_metaphone AKTN . and [ ] str:soundex_word Smith ; str:soundex S530 . I agree this is another way to model it, and Jeremy suggested it as well. But it creates a level of indirection and, from a modeling point of view, does look very weird. If you were to extend that model to, say, 1 list:in (1 2 3), that would look very nasty... Best, y are at least protected from collisions and allow more properties to be added in a safe way. Best Regards, Ivan Mikhailov OpenLink Software http://virtuoso.openlinksw.com
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On 2 Jul 2010, at 12:42, Richard Cyganiak wrote: Hi Yves, [trimmed cc list] On 2 Jul 2010, at 11:15, Yves Raimond wrote: I am not arguing for each vendor to implement that. I am arguing for removing this arbitrary limitation from the RDF spec. Also marked as an issue since 2000: http://www.w3.org/2000/03/rdf-tracking/#rdfms-literalsubjects The demand that W3C modify the specs to allow literals as subjects should be rejected on a simple principle: Those who demand that change, including yourself, have failed to put their money where their mouth is. Where is the alternative specification that documents the syntactic and semantic extension? Where are the proposed RDF/XML++ and RDFa++ that support literals as subjects? Where are the patches to Jena, Sesame, Redland and ARC2 that support these changes? The restriction seems to bother some people enough that they write noisy emails, but it apparently doesn't bother them enough to actually do anything about it. Sorry it is implemented in Cwm, and Euler sharp, and the N3 javascript parser in tabulator, and we hear about rules having them, and even them being allowed by the latest OWL 2 spec. Furthermore as argued it is not complicated to do allow existing systems to use this: take any ted chars 3 . and transform to [] sameas ted chars 3. There is even a language for it called N3, that is what SPARQL was based on. So I don't see why you have to be so agressive here. Henry
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Pat Hayes wrote:
On Jul 1, 2010, at 9:42 AM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 3:49 PM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or
however it is
called) claims could probably make a mess, if added or
removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just
about impossible to guarantee that messes can't happen when all
you are doing is describing structures in an open-world
setting. But I think the cure is to stop thinking that
possible-messes are a problem to be solved. So, there is dung
in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad
'linked data' practise by using examples like { 'London' a
x:Place } - whereas I'd immediately counter with { x:London a
'Place' }.
Surely all of the subjects as literals arguments can be
countered with 'walk round it', and further good practise could
be aided by a few simple notes on best practise for linked data
etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where
Subjects have Identifiers in the form of Name References (which
may or many resolve to Structured Representations of Referents
carried or borne by Descriptor Docs/Resources). An Identifier
!= Literal.
What ARE you talking about? You sound like someone reciting doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as URIs
are. They identify their value, most clearly and emphatically.
They denote in exactly the same way that URIs denote.
23^^xsd:number is about as good an identification of the
number twenty-three as you are ever likely to get in any
notational system since ancient Babylonia.
Yes, but ancient Bablyonia != World Wide Web of Structured Linked
Data, slightly different mediums with some shared characteristics :-)
The World Wide Web is becoming a Distributed DBMS (in my eyes).
Thus, unambiguous naming matters.
A topic for a longer discussion; but irrelevant here, since typed
literals are as unambiguous as a name can possibly get.
Literal Subjects aren't a show stopper per se. (esp. for local
RDF data). My gripe simply boils down to the nuisance factor
introduced by data object name ambiguity in a distributed data
object oriented realm such as the emerging Web of Linked Data.
What does 23^^xsd:number mean to anyone in a global data space?
It means the number twenty-three, everywhere and for all time,
because this meaning can be computed from the very syntactic form of
the name. How unambiguous can something get?
Pat,
Re. RDF's triples, What is a Subject? What is an Object?.
subject' refers to the first element in a triple, object to the
last. One might as well call them 'first' and 'third'. The names
'subject' and 'object' are used purely for convenience, and have no
formal or semantic significance.
If they are the same thing, why on earth do we use Names (with
implications) to describe the slots in an RDF triple?
I do not understand the question here well enough to provide an
answer. Have you actually read the RDF spec documents? The RDF syntax
model and the semantics?
You don't understand the question enough to provide an answer, but you
are able to compute an assessment of spec assimilation. WOW !!
I've only once seen the RDF triple referred to as O-R-O (by @danbri)
i.e., Object-Relation-Object.
IF you read the specs, however, it is abundantly clear that this is
what an RDF triple means, viz. that a relation holds between two
objects (I prefer things, but).
Exactly!
So why: Subject-Predicate-Object (SPO) everywhere re. RDF?
O-R-O reflects what you've just described.
Like many of the RDF oddities (playing out nicely in this thread), you
have an O-R-O but everyone talks about S-P-O.
Subject has implicit meaning, it lends itself to describing stuff. If
I recall, RDF stands for: Resource Description Framework.
I guess Description also means nothing?
In addition, I don't see Information and Data as being the same
thing. Information (as I know it) is about Data + Context. Raw Data
(as I know it) is about: a unit of observation and deemed worthy of
description by its observer. You have to give Names to subject of a
description. 23^^xsd:number isn't a Name.
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Hi Richard! [trimmed cc list] On 2 Jul 2010, at 11:15, Yves Raimond wrote: I am not arguing for each vendor to implement that. I am arguing for removing this arbitrary limitation from the RDF spec. Also marked as an issue since 2000: http://www.w3.org/2000/03/rdf-tracking/#rdfms-literalsubjects The demand that W3C modify the specs to allow literals as subjects should be rejected on a simple principle: Those who demand that change, including yourself, have failed to put their money where their mouth is. Where is the alternative specification that documents the syntactic and semantic extension? Where are the proposed RDF/XML++ and RDFa++ that support literals as subjects? Where are the patches to Jena, Sesame, Redland and ARC2 that support these changes? This is a really unfair comment, Richard, and I am sure you realise that. We are arguing for a very small modification of http://www.w3.org/TR/rdf-concepts/#section-Literals - not of any serialisation at the moment. Some of them happen to already support that (the RDF subset of N3). The serialisation work is outside of the scope of this discussion (but should happen, I agree) - let's stick to small, iterative, improvements and bug fixes. The restriction seems to bother some people enough that they write noisy emails, but it apparently doesn't bother them enough to actually do anything about it. Same thing - very unfair. We are being very specific about the change we want made. Some of us implemented patches and libraries supporting that (I wrote a swi-prolog one, Toby mentioned a Perl one, CWM supports it since ages, as well as all other N3 engines). So, please, if you want to criticise our proposal, do it on a sound basis, instead of just trying to get as many people as you can very frustrated at the way such decisions are being made. Also, putting forward the us vs. them argument is not really the best way to move forward, as I am sure you would agree. We suffered from that in the LOD community a lot (and as Dan points out, still suffer from that a lot in the whole Semantic Web community), so please stop sending such emails anytime you feel in opposition with a proposal, and let's have a fruitful debate. W3C's job should be to broker compromises between non-interoperable approaches by different vendors, and to foster adoption by putting its stamp of approval on already widely deployed technologies developed by the community. You know, the kind of stuff that actually came out near the top of the RDF Next Steps work item poll [1]: named graphs, Turtle, RDF/JSON. W3C's job is also to provide bug-free specs, and interoperable one. The fact that you can CONSTRUCT an invalid RDF document in SPARQL, whilst still being valid SPARQL, is bad IMHO. Someone mentioned HTML 3.2 in this thread. Let me mention the ill-fated XHTML 2.0. A group of markup purists who were more interested in polishing the arcane details of the language, rather than meeting the interests of the heaviest users and the vendors. They did an enormous disservice to W3C and the web. The users and vendors turned their back on W3C, started their own effort, and W3C ultimately had to abandon XHTML 2.0 or risk to become irrelevant to the future of HTML. Literals as subjects feels very much like an XHTML 2.0 kind of feature to me. Or, coming at it from a completely different direction: I have yet to meet a person (except Nathan perhaps) who says, Yeah that RDF stuff, I had a look at it but then saw that it does not support literals as subjects, so I gave up on it. The same reasoning can be applied to all the things in the current item poll: Turtle not existing didn't stop people publishing RDF/XML. Named Graphs not being spec'ed out didn't stop them either. So I would also argue this is a buggy argument, mostly there for drawing more FUD on a thread that, I think, doesn't need more. Best, y Best, Richard [1] http://www.w3.org/2010/06/rdf-work-items/table That aside, I don't see your point about extra hardware. There is, in my experience, no substantial difference between storing #me foaf:name Ivan and Ivan :name_of #me. _not_enough_unique_ to interlink data. There are. Their value is their identity. They are *perfectly* unique. cat is uniquely identifying the string made of c, a and t. From your previous email, I suppose you're concerned about rounding for floats and doubles, is that it? If so, whatever you write as their rounded value is their identity (and we can't write Pi^^xsd:real afaik :) ). [ ] str:double_metaphone_word Acton ; str:double_metaphone AKTN . and [ ] str:soundex_word Smith ; str:soundex S530 . I agree this is another way to model it, and Jeremy suggested it as well. But it creates a level of indirection and, from a modeling point of view, does look very weird. If you were to extend that model to, say, 1 list:in (1 2 3), that would look very nasty... Best, y are at least protected from collisions
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Fri, 2010-07-02 at 12:42 +0200, Richard Cyganiak wrote: Hi Yves, On 2 Jul 2010, at 11:15, Yves Raimond wrote: I am not arguing for each vendor to implement that. I am arguing for removing this arbitrary limitation from the RDF spec. Also marked as an issue since 2000: http://www.w3.org/2000/03/rdf-tracking/#rdfms-literalsubjects The demand that W3C modify the specs to allow literals as subjects should be rejected on a simple principle: Those who demand that change, including yourself, have failed to put their money where their mouth is. Where is the alternative specification that documents the syntactic and semantic extension? Where are the proposed RDF/XML++ and RDFa++ that support literals as subjects? Where are the patches to Jena, Sesame, Redland and ARC2 that support these changes? +1, with a small correction. I'd expect a patch for Virtuoso as well ;) Actually, the approval of a new spec will require two adequate implementations. I can't imagine that existing vendors will decide to waste their time to make their products worse in terms of speed and disk footprint and scalability. The most efficient critics is sabotage, you know. Some new vendor may of course try to become a strikebreaker but his benchmark runs will look quite poorly, because others will continue to optimize any SPARQL BGP like ?s ?p ?o . ?o ?p2 ?s2 . into more selective ?s ?p ?o . FILTER (isREFERENCE (?o)) . ?o ?p2 ?s2 . and this sort of rewriting will easily bring them two orders of magnitude of speed on a simple query with less than 10 triple patterns. Keeping in mind that Bio2RDF people tend to write queries with 20-30 triple patterns mostly connected into long chains, the speed difference on real life queries will be a blocking issue. - The discussion is quite long; I'm sorry I can't continue to track it accurately, I'm on a critical path of a new Virtuoso release. If somebody is interested in a whole list of reasons why I will not put this feature into the DB core or a whole list of workarounds for it at DB application level or a detailed history of round Earth and Columbus then ping me and I'll write a page at ESW wiki. Best Regards, Ivan Mikhailov OpenLink Virtuoso http://virtuoso.openlinksw.com
RE: Subjects as Literals, [was Re: The Ordered List Ontology]
Kingsley Idehen wrote: So why: Subject-Predicate-Object (SPO) everywhere re. RDF? O-R-O reflects what you've just described. Like many of the RDF oddities (playing out nicely in this thread), you have an O-R-O but everyone talks about S-P-O. Subject has implicit meaning, it lends itself to describing stuff. If I recall, RDF stands for: Resource Description Framework. I guess Description also means nothing? S-P-O typically refers to a syntactic aspect of RDF triples, while O-R-O refers to a semantic aspect. S-P-O: S (subject) stands for the first node in an RDF triple. P (predicate) for the second node. O (object) for the third node. The nodes and the triples are entities of the RDF Abstract Syntax. They don't have any semantic meaning on their own. O-R-O: In the RDF semantics, a syntactic RDF triple is interpreted as a relationship that holds between two individuals. The two Os refer the two individuals (or resources, or objects), being taken from the domain of discourse (the world, about which assertions are made). The R stands for the property (or relation; in any case a semantic entity) that is used to define the relationship between the two individuals. So, these are very different aspects that must not be confused. An S-P-O syntactic RDF triple is interpreted as a O-R-O semantic relationship between individuals. The S in S-P-O can be a URI, a bNode, and maybe also a literal in the future. The Os in O-R-O stand for entities in the world. A semantic interpretation function can then use the S to denote (to name) the O. But there is no a-priory connection between the two: any S-P-O triple can be interpreted by any O-R-O relationship. I think, the main confusion comes from the use of the term object for two entirely different things: In the case of O-R-O, it refers to (semantic) individuals. In the case of S-P-O, it refers to a position in a (syntactic) RDF triple. Michael -- Dipl.-Inform. Michael Schneider Research Scientist, Information Process Engineering (IPE) Tel : +49-721-9654-726 Fax : +49-721-9654-727 Email: michael.schnei...@fzi.de WWW : http://www.fzi.de/michael.schneider === FZI Forschungszentrum Informatik an der Universität Karlsruhe Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe Tel.: +49-721-9654-0, Fax: +49-721-9654-959 Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael Flor, Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus ===
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Michael Schneider wrote: Kingsley Idehen wrote: So why: Subject-Predicate-Object (SPO) everywhere re. RDF? O-R-O reflects what you've just described. Like many of the RDF oddities (playing out nicely in this thread), you have an O-R-O but everyone talks about S-P-O. Subject has implicit meaning, it lends itself to describing stuff. If I recall, RDF stands for: Resource Description Framework. I guess Description also means nothing? S-P-O typically refers to a syntactic aspect of RDF triples, while O-R-O refers to a semantic aspect. S-P-O: S (subject) stands for the first node in an RDF triple. P (predicate) for the second node. O (object) for the third node. The nodes and the triples are entities of the RDF Abstract Syntax. They don't have any semantic meaning on their own. O-R-O: In the RDF semantics, a syntactic RDF triple is interpreted as a relationship that holds between two individuals. The two Os refer the two individuals (or resources, or objects), being taken from the domain of discourse (the world, about which assertions are made). The R stands for the property (or relation; in any case a semantic entity) that is used to define the relationship between the two individuals. So, these are very different aspects that must not be confused. An S-P-O syntactic RDF triple is interpreted as a O-R-O semantic relationship between individuals. The S in S-P-O can be a URI, a bNode, and maybe also a literal in the future. The Os in O-R-O stand for entities in the world. A semantic interpretation function can then use the S to denote (to name) the O. But there is no a-priory connection between the two: any S-P-O triple can be interpreted by any O-R-O relationship. I think, the main confusion comes from the use of the term object for two entirely different things: In the case of O-R-O, it refers to (semantic) individuals. In the case of S-P-O, it refers to a position in a (syntactic) RDF triple. Conflation Conflation. It makes RDF a real PITA, unfortunately. EAV model is crystal clear: Entity-Attribute-Value. Slap on HTTP names for Entity, Attribute, and Value, optionally, and you get an HTTP based World Wide Web of Structured Linked Data. This is why conflating RDF and Linked Data has nothing but downside IMHO. Kingsley Michael -- Dipl.-Inform. Michael Schneider Research Scientist, Information Process Engineering (IPE) Tel : +49-721-9654-726 Fax : +49-721-9654-727 Email: michael.schnei...@fzi.de WWW : http://www.fzi.de/michael.schneider === FZI Forschungszentrum Informatik an der Universität Karlsruhe Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe Tel.: +49-721-9654-0, Fax: +49-721-9654-959 Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael Flor, Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus === -- Regards, Kingsley Idehen President CEO OpenLink Software Web: http://www.openlinksw.com Weblog: http://www.openlinksw.com/blog/~kidehen Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Henry Story wrote: On 2 Jul 2010, at 15:22, Kingsley Idehen wrote: I think, the main confusion comes from the use of the term object for two entirely different things: In the case of O-R-O, it refers to (semantic) individuals. In the case of S-P-O, it refers to a position in a (syntactic) RDF triple. Conflation Conflation. It makes RDF a real PITA, unfortunately. EAV model is crystal clear: Entity-Attribute-Value. Slap on HTTP names for Entity, Attribute, and Value, optionally, and you get an HTTP based World Wide Web of Structured Linked Data. This is why conflating RDF and Linked Data has nothing but downside IMHO. It all depends to whom one is speaking Kingsley. To me EAV does not say much. To OO programmers attribute values often gets them thinking somewhere along the right lines. Value is clearer than Object. A Value can be a Reference or a Literal. A Reference can be a Name or an Address. RDF (which I use extensively) is a problem when it comes to value proposition articulation. Its way too prone to the kind of thread that's making me miss Brazil vs. Netherlands (right now). Anyway, I am talking about the most basic foundation for Linked Data. It doens't need RDF overhang. Simple story: An HTTP Name for the things you deem worthy of describing and then sharing with others via a network (e.g. World Wide Web). Application of said Names to Description Subject, its Attributes, and Attribute Values. Do that and we can Link and Lookup stuff across an HTTP network, really simple! I think it may be best to think in terms of arrows between things, as shown below. I think since the 60ies everyone at the age of 5 starts learning about mappings between objects, these mappings are arrows, and are very easy to understand. All of these are ok with me. I also like RDF, it means many things, and most of all Reality Distortion Field. Because as you know, our view of reality is very distorted (just think of how people 2000 years ago saw the world), and so to get to understand things better we need to enter what will seem a reality distortion field from our very limited point of view. BTW -- Richard packs a goatee these days. Need a temporal dimension for richer representation LOL! Kingsley Henry -- Regards, Kingsley Idehen President CEO OpenLink Software Web: http://www.openlinksw.com Weblog: http://www.openlinksw.com/blog/~kidehen Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Richard Cyganiak wrote: Hi Yves, [trimmed cc list] On 2 Jul 2010, at 11:15, Yves Raimond wrote: I am not arguing for each vendor to implement that. I am arguing for removing this arbitrary limitation from the RDF spec. Also marked as an issue since 2000: http://www.w3.org/2000/03/rdf-tracking/#rdfms-literalsubjects The demand that W3C modify the specs to allow literals as subjects should be rejected on a simple principle: Those who demand that change, including yourself, have failed to put their money where their mouth is. Where is the alternative specification that documents the syntactic and semantic extension? Where are the proposed RDF/XML++ and RDFa++ that support literals as subjects? Where are the patches to Jena, Sesame, Redland and ARC2 that support these changes? The restriction seems to bother some people enough that they write noisy emails, but it apparently doesn't bother them enough to actually do anything about it. W3C's job should be to broker compromises between non-interoperable approaches by different vendors, and to foster adoption by putting its stamp of approval on already widely deployed technologies developed by the community. You know, the kind of stuff that actually came out near the top of the RDF Next Steps work item poll [1]: named graphs, Turtle, RDF/JSON. Someone mentioned HTML 3.2 in this thread. Let me mention the ill-fated XHTML 2.0. A group of markup purists who were more interested in polishing the arcane details of the language, rather than meeting the interests of the heaviest users and the vendors. They did an enormous disservice to W3C and the web. The users and vendors turned their back on W3C, started their own effort, and W3C ultimately had to abandon XHTML 2.0 or risk to become irrelevant to the future of HTML. Literals as subjects feels very much like an XHTML 2.0 kind of feature to me. Or, coming at it from a completely different direction: I have yet to meet a person (except Nathan perhaps) who says, Yeah that RDF stuff, I had a look at it but then saw that it does not support literals as subjects, so I gave up on it. To clarify - I certainly am not giving up on RDF, and RDF (with the exception of Graph Literals) *does* support everything I need (including literals as subjects) - however I am having to give up on restricting myself to only using the constrained subset of RDF provided by the common serializations. I've found, that in order to be productive and actually make real applications running over a read/write web of linked data I'll need the most of the full RDF model those graph literals - in other words N3 provides everything I need [*] to be able to leave the issues behind and just get on being productive (and hopefully a little bit innovative). I can, and will still publish and consume the common serializations of RDF we all use, but to use the data functionally in an application I need N3 too. * tooling is poor of course so far.. but Toby has already stated he's wanting to implement in Perl, Yves has already started years ago, TimBL, DanC obviously with CWM, others I'm sure, and I'm certainly going to address an implementation for ECMAScript-262 (as are some MIT'ers) on client and server and quite possibly port to PHP for ARC2 (although that's sometime off and isn't a promise), many others have expressed the same sentiments over the last day or two alone - so tooling won't be an issue for too long, just as it isn't now for the other RDF serializations but was years ago. Hope that clarifies :) ps: fwiw, I'm with Ian, Toby, Henry and many others on this - leave the existing serializations alone, they are only a subset but they do the job quite well and let us publish and consume linked data - so it's all cool - changing the serializations and stack that's out there is an (imho) ridiculously bad idea that will benefit nobody, and it needs dropped from all these conversations - the original thread was from me, to clarify if subjects as literals were supported by the RDF Semantics, and they are, as if virtually anything in any position so it's a non issue, and certainly wasn't the issue everybodies hooked up on about changing rdf/xml and the likes. Best, Nathan
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jul 2, 2010, at 6:52 AM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jul 1, 2010, at 9:42 AM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 3:49 PM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or
however it is
called) claims could probably make a mess, if added or
removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures
using pointers, which is what the RDF vocabulary describes.
Its just about impossible to guarantee that messes can't
happen when all you are doing is describing structures in an
open-world setting. But I think the cure is to stop thinking
that possible-messes are a problem to be solved. So, there
is dung in the road. Walk round it.
Could we also apply that to the 'subjects as literals'
general discussion that's going on then?
For example I've heard people saying that it encourages bad
'linked data' practise by using examples like { 'London' a
x:Place } - whereas I'd immediately counter with { x:London a
'Place' }.
Surely all of the subjects as literals arguments can be
countered with 'walk round it', and further good practise
could be aided by a few simple notes on best practise for
linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where
Subjects have Identifiers in the form of Name References
(which may or many resolve to Structured Representations of
Referents carried or borne by Descriptor Docs/Resources). An
Identifier != Literal.
What ARE you talking about? You sound like someone reciting
doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as
URIs are. They identify their value, most clearly and
emphatically. They denote in exactly the same way that URIs
denote. 23^^xsd:number is about as good an identification
of the number twenty-three as you are ever likely to get in any
notational system since ancient Babylonia.
Yes, but ancient Bablyonia != World Wide Web of Structured
Linked Data, slightly different mediums with some shared
characteristics :-)
The World Wide Web is becoming a Distributed DBMS (in my eyes).
Thus, unambiguous naming matters.
A topic for a longer discussion; but irrelevant here, since typed
literals are as unambiguous as a name can possibly get.
Literal Subjects aren't a show stopper per se. (esp. for local
RDF data). My gripe simply boils down to the nuisance factor
introduced by data object name ambiguity in a distributed data
object oriented realm such as the emerging Web of Linked Data.
What does 23^^xsd:number mean to anyone in a global data
space?
It means the number twenty-three, everywhere and for all time,
because this meaning can be computed from the very syntactic form
of the name. How unambiguous can something get?
Pat,
Re. RDF's triples, What is a Subject? What is an Object?.
subject' refers to the first element in a triple, object to the
last. One might as well call them 'first' and 'third'. The names
'subject' and 'object' are used purely for convenience, and have no
formal or semantic significance.
If they are the same thing, why on earth do we use Names (with
implications) to describe the slots in an RDF triple?
I do not understand the question here well enough to provide an
answer. Have you actually read the RDF spec documents? The RDF
syntax model and the semantics?
You don't understand the question enough to provide an answer, but
you are able to compute an assessment of spec assimilation. WOW !!
The logic here is: if you had understood the specs, you wouldn't be
asking such a damn silly question as you appear to be asking. So, I
conclude to myself, I must be misunderstanding your question. Unless,
of course, you havn't actually read the specs...
I've only once seen the RDF triple referred to as O-R-O (by
@danbri) i.e., Object-Relation-Object.
IF you read the specs, however, it is abundantly clear that this is
what an RDF triple means, viz. that a relation holds between two
objects (I prefer things, but).
Exactly!
? I thought you were arguing *against* this view ?
So why: Subject-Predicate-Object (SPO) everywhere re. RDF?
As I said, the terminology is used so as to make it easier to refer to
the various parts of a triple. Yes, triples are ordered. The
'linguistic' flavor of the SPO terminology is an unfortunate accident
of history. In other forums, people
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Pat Hayes wrote:
On Jul 2, 2010, at 6:52 AM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jul 1, 2010, at 9:42 AM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 3:49 PM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or
however it is
called) claims could probably make a mess, if added or
removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its
just about impossible to guarantee that messes can't happen
when all you are doing is describing structures in an
open-world setting. But I think the cure is to stop thinking
that possible-messes are a problem to be solved. So, there is
dung in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad
'linked data' practise by using examples like { 'London' a
x:Place } - whereas I'd immediately counter with { x:London a
'Place' }.
Surely all of the subjects as literals arguments can be
countered with 'walk round it', and further good practise
could be aided by a few simple notes on best practise for
linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where
Subjects have Identifiers in the form of Name References
(which may or many resolve to Structured Representations of
Referents carried or borne by Descriptor Docs/Resources). An
Identifier != Literal.
What ARE you talking about? You sound like someone reciting
doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as
URIs are. They identify their value, most clearly and
emphatically. They denote in exactly the same way that URIs
denote. 23^^xsd:number is about as good an identification of
the number twenty-three as you are ever likely to get in any
notational system since ancient Babylonia.
Yes, but ancient Bablyonia != World Wide Web of Structured Linked
Data, slightly different mediums with some shared characteristics
:-)
The World Wide Web is becoming a Distributed DBMS (in my eyes).
Thus, unambiguous naming matters.
A topic for a longer discussion; but irrelevant here, since typed
literals are as unambiguous as a name can possibly get.
Literal Subjects aren't a show stopper per se. (esp. for local
RDF data). My gripe simply boils down to the nuisance factor
introduced by data object name ambiguity in a distributed data
object oriented realm such as the emerging Web of Linked Data.
What does 23^^xsd:number mean to anyone in a global data space?
It means the number twenty-three, everywhere and for all time,
because this meaning can be computed from the very syntactic form
of the name. How unambiguous can something get?
Pat,
Re. RDF's triples, What is a Subject? What is an Object?.
subject' refers to the first element in a triple, object to the
last. One might as well call them 'first' and 'third'. The names
'subject' and 'object' are used purely for convenience, and have no
formal or semantic significance.
If they are the same thing, why on earth do we use Names (with
implications) to describe the slots in an RDF triple?
I do not understand the question here well enough to provide an
answer. Have you actually read the RDF spec documents? The RDF
syntax model and the semantics?
You don't understand the question enough to provide an answer, but
you are able to compute an assessment of spec assimilation. WOW !!
The logic here is: if you had understood the specs, you wouldn't be
asking such a damn silly question as you appear to be asking. So, I
conclude to myself, I must be misunderstanding your question. Unless,
of course, you havn't actually read the specs...
Pat,
Assume I've read the spec and don't understand them. Rather that
gravitating to insults, just answer the question I asked.
If too silly or dumb for you, you do have the option to ignore.
Where I come from there are no silly or dumb questions. Instead, it
rather silly or dumb to not ask questions when pursuing clarity.
So far so good, you have spewed subjective commentary and unnecessary
insults.
You can have a conversation without being insulting, you know.
I've only once seen the RDF triple referred to as O-R-O (by
@danbri) i.e., Object-Relation-Object.
IF you read the specs, however, it is abundantly clear that this is
what an RDF triple
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
[snip] This is the second time in a few hours that a thread has degenerated into talk of accusations and insults. I don't care who started it. Sometimes email just isn't the best way to communicate. If people are feeling this way about an email discussion, it might be worth the respective parties spending a few minutes on the phone to try to smooth things over. Or not. I don't care, really. But each of these mail messages is getting distributed to several hundred readers. It would be good if we can find ways of using that bandwidth to solve problems rather than get into fights. Or maybe we should all just take a weekend break, mull things over for a couple of days, and start fresh on monday? That's my plan anyhow... cheers, Dan
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On 7/2/2010 12:00 PM, Dan Brickley wrote: Or maybe we should all just take a weekend break, mull things over for a couple of days, and start fresh on monday? That's my plan anyhow... Yeah, maybe some of us could meet up in some sunny place and sit in an office, maybe at Stanford - just like last weekend! Jeremy
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Fri, Jul 2, 2010 at 8:34 PM, Jeremy Carroll jer...@topquadrant.com wrote: On 7/2/2010 12:00 PM, Dan Brickley wrote: Or maybe we should all just take a weekend break, mull things over for a couple of days, and start fresh on monday? That's my plan anyhow... Yeah, maybe some of us could meet up in some sunny place and sit in an office, maybe at Stanford - just like last weekend! I have to say that meeting was a lot more civilised than the current raging debate on these lists! Jeremy Ian
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Dan Brickley wrote: [snip] This is the second time in a few hours that a thread has degenerated into talk of accusations and insults. I don't care who started it. Sometimes email just isn't the best way to communicate. If people are feeling this way about an email discussion, it might be worth the respective parties spending a few minutes on the phone to try to smooth things over. Or not. I don't care, really. But each of these mail messages is getting distributed to several hundred readers. It would be good if we can find ways of using that bandwidth to solve problems rather than get into fights. Or maybe we should all just take a weekend break, mull things over for a couple of days, and start fresh on monday? That's my plan anyhow... cheers, Dan Dan, Being civil isn't rocket science. People can debate, even do so with passion. All doable without unnecessary insults. Ghana has certainly knocked me out anyhow :-( -- Regards, Kingsley Idehen President CEO OpenLink Software Web: http://www.openlinksw.com Weblog: http://www.openlinksw.com/blog/~kidehen Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On 2010/7/1 22:42, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 3:49 PM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however
it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just
about impossible to guarantee that messes can't happen when all
you are doing is describing structures in an open-world setting.
But I think the cure is to stop thinking that possible-messes
are a problem to be solved. So, there is dung in the road. Walk
round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad
'linked data' practise by using examples like { 'London' a
x:Place } - whereas I'd immediately counter with { x:London a
'Place' }.
Surely all of the subjects as literals arguments can be countered
with 'walk round it', and further good practise could be aided by
a few simple notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects
have Identifiers in the form of Name References (which may or many
resolve to Structured Representations of Referents carried or
borne by Descriptor Docs/Resources). An Identifier != Literal.
What ARE you talking about? You sound like someone reciting doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as URIs
are. They identify their value, most clearly and emphatically. They
denote in exactly the same way that URIs denote. 23^^xsd:number
is about as good an identification of the number twenty-three as
you are ever likely to get in any notational system since ancient
Babylonia.
Yes, but ancient Bablyonia != World Wide Web of Structured Linked
Data, slightly different mediums with some shared characteristics :-)
The World Wide Web is becoming a Distributed DBMS (in my eyes).
Thus, unambiguous naming matters.
A topic for a longer discussion; but irrelevant here, since typed
literals are as unambiguous as a name can possibly get.
Literal Subjects aren't a show stopper per se. (esp. for local RDF
data). My gripe simply boils down to the nuisance factor introduced
by data object name ambiguity in a distributed data object oriented
realm such as the emerging Web of Linked Data.
What does 23^^xsd:number mean to anyone in a global data space?
It means the number twenty-three, everywhere and for all time,
because this meaning can be computed from the very syntactic form of
the name. How unambiguous can something get?
Pat,
Re. RDF's triples, What is a Subject? What is an Object?.
If they are the same thing, why on earth do we use Names (with
implications) to describe the slots in an RDF triple?
I've only once seen the RDF triple referred to as O-R-O (by @danbri)
i.e., Object-Relation-Object.
In addition, I don't see Information and Data as being the same thing.
Information (as I know it) is about Data + Context. Raw Data (as I
know it) is about: a unit of observation and deemed worthy of
description by its observer. You have to give Names to subject of a
description. 23^^xsd:number isn't a Name.
**
I guess my own subtle mistake (re. this thread) is deeming Identifiers
and Names to be equivalent , when they aren't :-) Of course, one can
use an Identifier as a Name, but that doesn't make them equivalent.
**
One clear point of divergence here is that I am focused on the Web as
Dist. DBMS that leverages 3-tuples + HTTP URIs in the S, P, and
optionally O slot (aka. HTTP based Linked Data).
To conclude:
Name != Identifier.
We can also question the role of URI. Because the location of resource
pointed by URI and the content of URI are orthogonal. A location is
interpreted by a set of locating operations, the locating result is
only GUIDED, not CONTROLLED, by the content of URI. To realize this is
very important!
regards
Peng
I believe Subject == Name (an Identifier based Name) re. RDF triples
otherwise the triple should be described as: O-R-O or O-P-O.
I believe an S-P-O triple is a piece of information (Data Object has a
Name and at least one Attribute=Value pair).
What I desscribe actually has zilch to do with RDF as I am inclined to
believe you see RDF :-) Thus, in a way, the literal-subject
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On 2010/7/1 22:35, Kingsley Idehen wrote:
Yves Raimond wrote:
Hello Kingsley!
[snip]
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many
resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
It does look like you're already using literal subjects in OpenLink
Virtuoso though:
http://docs.openlinksw.com/virtuoso/rdfsparql.html
SQLSELECT *
FROM people
WHERE
{
?s foaf:Name ?name . ?name bif:contains 'rich*'.
}
Best,
y
Were is the Literal Subject in the query above?
bif:contains is a function/magic predicate scoped to Literal Objects.
people != people.
Let's consider the following inequality:
people != people
if we imposed different interpretations on both sides，then we certainly
could conclude the first 'people' is non-equivalence to the second
'people' in semantic. Semantic of things is not reflected in the literal
meaning, but is reflected in interpreter's behavior and its impact on
the environment/world.
my two cents.
regards
Peng
What am I missing?
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On 30 Jun 2010, at 21:09, Pat Hayes wrote:
For example I've heard people saying that it encourages bad 'linked data'
practise by using examples like { 'London' a x:Place } - whereas I'd
immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered with 'walk
round it', and further good practise could be aided by a few simple notes on
best practise for linked data etc.
I wholly agree. Allowing literals in subject position in RDF is a no-brainer.
(BTW, it would also immediately solve the 'bugs in the RDF rules' problem.)
These arguments against it are nonsensical. The REAL argument against it is
that it will mess up OWL-DL, or at any rate it *might* mess up OWL-DL.
The Description Logic police are still in charge:-)
I agree that literals can be subjects. In any case they are, because you just
can take an inverse function from a thing to a string, and you have it.
But I do think
'London' a x:Place
is bad design because really 'London' is a string and not a place.
Now of course x:Place my be the collection of names of places in english, in
which case it is ok. So it is difficult to say just like that. There would have
to be quite a lot of education in the when is it right to use strings as
subjects space.
Henry
Pat
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Yves Raimond wrote:
Hello Kingsley!
[snip]
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
It does look like you're already using literal subjects in OpenLink
Virtuoso though:
http://docs.openlinksw.com/virtuoso/rdfsparql.html
SQLSELECT *
FROM people
WHERE
{
?s foaf:Name ?name . ?name bif:contains 'rich*'.
}
Best,
y
Were is the Literal Subject in the query above?
bif:contains is a function/magic predicate scoped to Literal Objects.
people != people.
What am I missing?
--
Regards,
Kingsley Idehen
President CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Pat Hayes wrote:
On Jun 30, 2010, at 3:49 PM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however
it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just
about impossible to guarantee that messes can't happen when all
you are doing is describing structures in an open-world setting.
But I think the cure is to stop thinking that possible-messes are
a problem to be solved. So, there is dung in the road. Walk round
it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad
'linked data' practise by using examples like { 'London' a x:Place
} - whereas I'd immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered
with 'walk round it', and further good practise could be aided by
a few simple notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects
have Identifiers in the form of Name References (which may or many
resolve to Structured Representations of Referents carried or borne
by Descriptor Docs/Resources). An Identifier != Literal.
What ARE you talking about? You sound like someone reciting doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as URIs
are. They identify their value, most clearly and emphatically. They
denote in exactly the same way that URIs denote. 23^^xsd:number
is about as good an identification of the number twenty-three as you
are ever likely to get in any notational system since ancient
Babylonia.
Yes, but ancient Bablyonia != World Wide Web of Structured Linked
Data, slightly different mediums with some shared characteristics :-)
The World Wide Web is becoming a Distributed DBMS (in my eyes). Thus,
unambiguous naming matters.
A topic for a longer discussion; but irrelevant here, since typed
literals are as unambiguous as a name can possibly get.
Literal Subjects aren't a show stopper per se. (esp. for local RDF
data). My gripe simply boils down to the nuisance factor introduced
by data object name ambiguity in a distributed data object oriented
realm such as the emerging Web of Linked Data.
What does 23^^xsd:number mean to anyone in a global data space?
It means the number twenty-three, everywhere and for all time, because
this meaning can be computed from the very syntactic form of the name.
How unambiguous can something get?
Pat,
Re. RDF's triples, What is a Subject? What is an Object?.
If they are the same thing, why on earth do we use Names (with
implications) to describe the slots in an RDF triple?
I've only once seen the RDF triple referred to as O-R-O (by @danbri)
i.e., Object-Relation-Object.
In addition, I don't see Information and Data as being the same thing.
Information (as I know it) is about Data + Context. Raw Data (as I know
it) is about: a unit of observation and deemed worthy of description by
its observer. You have to give Names to subject of a description.
23^^xsd:number isn't a Name.
**
I guess my own subtle mistake (re. this thread) is deeming Identifiers
and Names to be equivalent , when they aren't :-) Of course, one can use
an Identifier as a Name, but that doesn't make them equivalent.
**
One clear point of divergence here is that I am focused on the Web as
Dist. DBMS that leverages 3-tuples + HTTP URIs in the S, P, and
optionally O slot (aka. HTTP based Linked Data).
To conclude:
Name != Identifier.
I believe Subject == Name (an Identifier based Name) re. RDF triples
otherwise the triple should be described as: O-R-O or O-P-O.
I believe an S-P-O triple is a piece of information (Data Object has a
Name and at least one Attribute=Value pair).
What I desscribe actually has zilch to do with RDF as I am inclined to
believe you see RDF :-) Thus, in a way, the literal-subject debate may
simply help everyone understand and accept that RDF != Linked Data.
Thus, providing additional proof that RDF isn't mandatory or even
required re. delivery of HTTP based Linked Data.
RDF based Linked Data != RDF. They are different things, clearly. We
can't have it both ways (** Pat: not for you, that's for those that deem
RDF and Linked
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On 1 Jul 2010, at 16:35, Kingsley Idehen wrote:
Yves Raimond wrote:
Hello Kingsley!
[snip]
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
It does look like you're already using literal subjects in OpenLink
Virtuoso though:
http://docs.openlinksw.com/virtuoso/rdfsparql.html
SQLSELECT *
FROM people
WHERE
{
?s foaf:Name ?name . ?name bif:contains 'rich*'.
}
Best,
y
Were is the Literal Subject in the query above?
bif:contains is a function/magic predicate scoped to Literal Objects.
people != people.
What am I missing?
Why do you think it is magic? Such a relation makes complete sense.
Given that is is a relation between literals it can be tested without needing
to look at the world. Just like an math:isgreaterThan relation ...
In fact I wonder how much SPARQL could be simplified by thinking of things this
way. Could one perhaps get rid of the FILTER( ) clause?
In any case RDF Semantics does, I believe,
allow literals in subject position. It is just that many many syntaxes
don't allow that to be expressed,
But there is nothing you can do to stop that happening semantically. A URI or
bnode
can just be names for strings.
And as for it requiring a change to the infrastructure of your DB, it is not
clear that
it immediately does, since you can alwasy rewrite
father containsLetters 6 .
as
[] owl:sameAs father;
containsLetters 6 .
Henry
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Hello!
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
It does look like you're already using literal subjects in OpenLink
Virtuoso though:
http://docs.openlinksw.com/virtuoso/rdfsparql.html
SQLSELECT *
FROM people
WHERE
{
?s foaf:Name ?name . ?name bif:contains 'rich*'.
}
Best,
y
Were is the Literal Subject in the query above?
?name is a literal. And it is used as a subject.
Best,
y
bif:contains is a function/magic predicate scoped to Literal Objects.
people != people.
What am I missing?
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Henry Story wrote:
On 1 Jul 2010, at 16:35, Kingsley Idehen wrote:
Yves Raimond wrote:
Hello Kingsley!
[snip]
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
It does look like you're already using literal subjects in OpenLink
Virtuoso though:
http://docs.openlinksw.com/virtuoso/rdfsparql.html
SQLSELECT *
FROM people
WHERE
{
?s foaf:Name ?name . ?name bif:contains 'rich*'.
}
Best,
y
Were is the Literal Subject in the query above?
bif:contains is a function/magic predicate scoped to Literal Objects.
people != people.
What am I missing?
Why do you think it is magic? Such a relation makes complete sense.
It's a virtuoso function surfaced as a predicate.
magic predicate was an initial moniker used at creation time.
bif:contains doesn't exist in pure triple form etc..
Given that is is a relation between literals it can be tested without needing
to look at the world. Just like an math:isgreaterThan relation ...
In fact I wonder how much SPARQL could be simplified by thinking of things this
way. Could one perhaps get rid of the FILTER( ) clause?
In any case RDF Semantics does, I believe,
allow literals in subject position. It is just that many many syntaxes
don't allow that to be expressed,
But there is nothing you can do to stop that happening semantically. A URI or
bnode
can just be names for strings.
And as for it requiring a change to the infrastructure of your DB, it is not
clear that
it immediately does, since you can alwasy rewrite
father containsLetters 6 .
as
[] owl:sameAs father;
containsLetters 6 .
DBMS wise, indexing is an issue which ultimately leads to data access
performance problems etc.. Steve already covered that ditto Ivan in
earlier comments, I believe.
In Virtuoso an IRI is a native type with implications as per comment above.
Kingsley
Henry
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
--
Regards,
Kingsley Idehen
President CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Thu, Jul 1, 2010 at 5:22 PM, Kingsley Idehen kide...@openlinksw.com wrote:
Henry Story wrote:
On 1 Jul 2010, at 16:35, Kingsley Idehen wrote:
Yves Raimond wrote:
Hello Kingsley!
[snip]
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve
to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
It does look like you're already using literal subjects in OpenLink
Virtuoso though:
http://docs.openlinksw.com/virtuoso/rdfsparql.html
SQLSELECT *
FROM people
WHERE
{
?s foaf:Name ?name . ?name bif:contains 'rich*'.
}
Best,
y
Were is the Literal Subject in the query above?
bif:contains is a function/magic predicate scoped to Literal Objects.
people != people.
What am I missing?
Why do you think it is magic? Such a relation makes complete sense.
It's a virtuoso function surfaced as a predicate.
magic predicate was an initial moniker used at creation time.
bif:contains doesn't exist in pure triple form etc..
Why couldn't it? For example, you may want to express exactly what
triple lead you to give a particular result, and within that scope you
may end up having to write: Brickley bif:contains ckley in RDF.
Forbidding literals as subjects makes this statement impossible to
express, however that's a very sensible thing you may want to express.
There are also lots of literal search examples that comes to mind:
Acton str:double_metaphone AKTN .
Smith str:soundex S530 .
...
Best,
y
Given that is is a relation between literals it can be tested without
needing
to look at the world. Just like an math:isgreaterThan relation ...
In fact I wonder how much SPARQL could be simplified by thinking of things
this
way. Could one perhaps get rid of the FILTER( ) clause?
In any case RDF Semantics does, I believe, allow literals in subject
position. It is just that many many syntaxes
don't allow that to be expressed,
But there is nothing you can do to stop that happening semantically. A
URI or bnode
can just be names for strings.
And as for it requiring a change to the infrastructure of your DB, it is
not clear that
it immediately does, since you can alwasy rewrite
father containsLetters 6 .
as
[] owl:sameAs father;
containsLetters 6 .
DBMS wise, indexing is an issue which ultimately leads to data access
performance problems etc.. Steve already covered that ditto Ivan in earlier
comments, I believe.
In Virtuoso an IRI is a native type with implications as per comment above.
Kingsley
Henry
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Yves Raimond wrote:
Hello!
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
It does look like you're already using literal subjects in OpenLink
Virtuoso though:
http://docs.openlinksw.com/virtuoso/rdfsparql.html
SQLSELECT *
FROM people
WHERE
{
?s foaf:Name ?name . ?name bif:contains 'rich*'.
}
Best,
y
Were is the Literal Subject in the query above?
?name is a literal. And it is used as a subject.
Yves,
Here's why its deemed magic/function/unreal predicate (a function
selectively working on literal data associated with the URI):
1. http://bit.ly/cQJTWQ -- SPARQL Query Results Page
2. http://bit.ly/acQc4u -- Actual SPARQL Query
There isn't an actual Literal Subject in the Virtuoso RDF DBMS. The
RDF_QUAD Table explicitly has Column S set to type IRI.
Here is the actual SQL DML for RDF_QUAD:
create table DB.DBA.RDF_QUAD
(
P IRI_ID,
S IRI_ID,
O ANY,
G IRI_ID,
PRIMARY KEY (P, S, O, G)
);
Kingsley
Best,
y
bif:contains is a function/magic predicate scoped to Literal Objects.
people != people.
What am I missing?
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
--
Regards,
Kingsley Idehen
President CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Thu, Jul 1, 2010 at 5:45 PM, Henry Story henry.st...@gmail.com wrote: On 1 Jul 2010, at 18:18, Yves Raimond wrote: In any case RDF Semantics does, I believe, allow literals in subject position. It is just that many many syntaxes don't allow that to be expressed, It doesn't seem to be allowed in the RDF semantics: http://www.w3.org/TR/rdf-concepts/#section-Literals A literal may be the object of an RDF statement, but not the subject or the predicate. Yes, but a bnode or a URI can refer to a literal. So if those can refer to a literal, then instead of writing [1] _:n1 owl:sameAs hello; numLetters 5 . Why not also allow one to write [2] hello numLetters 5. ? That is what I meant. In any case one can always map [2] to [1], so I am not sure the costs of allowing [2] need be that high. Every current implementation could just parse [2] and write it out as [1]. No? It just seems that [2] is a more concise way of writing things, and it is conceptually cleaner. I definitely agree... For my thesis work, I had to store quite a lot of signal processing computations in RDF, and had to hack a few triple stores (mainly SWI's one) to handle literals as subjects. I used a similar hack to do that, it was very easy to implement... y
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jul 1, 2010, at 3:38 AM, Henry Story wrote:
On 30 Jun 2010, at 21:09, Pat Hayes wrote:
For example I've heard people saying that it encourages bad
'linked data' practise by using examples like { 'London' a
x:Place } - whereas I'd immediately counter with { x:London a
'Place' }.
Surely all of the subjects as literals arguments can be countered
with 'walk round it', and further good practise could be aided by
a few simple notes on best practise for linked data etc.
I wholly agree. Allowing literals in subject position in RDF is a
no-brainer. (BTW, it would also immediately solve the 'bugs in the
RDF rules' problem.) These arguments against it are nonsensical.
The REAL argument against it is that it will mess up OWL-DL, or at
any rate it *might* mess up OWL-DL.
The Description Logic police are still in charge:-)
I agree that literals can be subjects. In any case they are, because
you just can take an inverse function from a thing to a string, and
you have it.
But I do think
'London' a x:Place
is bad design because really 'London' is a string and not a place.
Absolutely. That triple plus a reasonably sensible ontology of places
plus a basic RDFS reasoner should flag a contradiction fairly directly.
Pat
Now of course x:Place my be the collection of names of places in
english, in which case it is ok. So it is difficult to say just like
that. There would have to be quite a lot of education in the when is
it right to use strings as subjects space.
Henry
Pat
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
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Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jul 1, 2010, at 9:42 AM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 3:49 PM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or
however it is
called) claims could probably make a mess, if added or
removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its
just about impossible to guarantee that messes can't happen
when all you are doing is describing structures in an open-
world setting. But I think the cure is to stop thinking that
possible-messes are a problem to be solved. So, there is dung
in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad
'linked data' practise by using examples like { 'London' a
x:Place } - whereas I'd immediately counter with { x:London a
'Place' }.
Surely all of the subjects as literals arguments can be
countered with 'walk round it', and further good practise could
be aided by a few simple notes on best practise for linked data
etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where
Subjects have Identifiers in the form of Name References
(which may or many resolve to Structured Representations of
Referents carried or borne by Descriptor Docs/Resources). An
Identifier != Literal.
What ARE you talking about? You sound like someone reciting
doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as URIs
are. They identify their value, most clearly and emphatically.
They denote in exactly the same way that URIs denote.
23^^xsd:number is about as good an identification of the
number twenty-three as you are ever likely to get in any
notational system since ancient Babylonia.
Yes, but ancient Bablyonia != World Wide Web of Structured Linked
Data, slightly different mediums with some shared
characteristics :-)
The World Wide Web is becoming a Distributed DBMS (in my eyes).
Thus, unambiguous naming matters.
A topic for a longer discussion; but irrelevant here, since typed
literals are as unambiguous as a name can possibly get.
Literal Subjects aren't a show stopper per se. (esp. for local
RDF data). My gripe simply boils down to the nuisance factor
introduced by data object name ambiguity in a distributed data
object oriented realm such as the emerging Web of Linked Data.
What does 23^^xsd:number mean to anyone in a global data space?
It means the number twenty-three, everywhere and for all time,
because this meaning can be computed from the very syntactic form
of the name. How unambiguous can something get?
Pat,
Re. RDF's triples, What is a Subject? What is an Object?.
subject' refers to the first element in a triple, object to the
last. One might as well call them 'first' and 'third'. The names
'subject' and 'object' are used purely for convenience, and have no
formal or semantic significance.
If they are the same thing, why on earth do we use Names (with
implications) to describe the slots in an RDF triple?
I do not understand the question here well enough to provide an
answer. Have you actually read the RDF spec documents? The RDF syntax
model and the semantics?
I've only once seen the RDF triple referred to as O-R-O (by @danbri)
i.e., Object-Relation-Object.
IF you read the specs, however, it is abundantly clear that this is
what an RDF triple means, viz. that a relation holds between two
objects (I prefer things, but).
In addition, I don't see Information and Data as being the same
thing. Information (as I know it) is about Data + Context. Raw Data
(as I know it) is about: a unit of observation and deemed worthy of
description by its observer. You have to give Names to subject of a
description. 23^^xsd:number isn't a Name.
Why do you say this? It is certainly as much a name as, say, Patrick
J. Hayes. It is a well-formed string which denotes something, and its
denotation is perfectly clear, in fact computable. So, it is a name. I
challenge you to specify what you mean by Name in such a way that it
excludes literals as names, other than by simply reiterating your bare
claim that they are not.
**
I guess my own subtle mistake (re. this thread) is deeming
Identifiers and Names to be equivalent , when they aren't
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Pat Hayes wrote: On Jul 1, 2010, at 11:18 AM, Yves Raimond wrote: A literal may be the object of an RDF statement, but not the subject or the predicate. Just to clarify, this is a purely syntactic restriction. Allowing literals in subject position would require **no change at all** to the RDF semantics. (The non-normative inference rules for RDF and RDFS and D-entailment given in the semantics document would need revision, but they would then be simplified.) I have to wonder then, what can one all place in the s,p,o slots without changing the RDF semantics? literal and bnode predicates for instance? variables or formulae as in n3? read as: if a new serialization/syntax was defined for RDF what are the limitations for the values of node/object and relationship specified by the RDF Semantics? Best, Nathan ps: apologies if this is a dumb question, I fear i'd still be hear next year trying to answer it myself though ;)
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jul 2, 2010, at 12:07 AM, Nathan wrote: Pat Hayes wrote: On Jul 1, 2010, at 11:49 PM, Nathan wrote: Pat Hayes wrote: On Jul 1, 2010, at 11:18 AM, Yves Raimond wrote: A literal may be the object of an RDF statement, but not the subject or the predicate. Just to clarify, this is a purely syntactic restriction. Allowing literals in subject position would require **no change at all** to the RDF semantics. (The non-normative inference rules for RDF and RDFS and D-entailment given in the semantics document would need revision, but they would then be simplified.) I have to wonder then, what can one all place in the s,p,o slots without changing the RDF semantics? literal and bnode predicates for instance? variables or formulae as in n3? read as: if a new serialization/syntax was defined for RDF what are the limitations for the values of node/object and relationship specified by the RDF Semantics? None at all. The semantics as stated works fine with triples which have any kind of syntactic node in any position in any combination. The same basic semantic construction is used in ISO Common Logic, which allows complete syntactic freedom, so that the the same name can denote an individual, a property, a function and a proposition all at the same time. Pat PS. Its not a dumb question :-) thus is N3 valid RDF? (I read yes, but want/need to hear that's right!) Well, no. It depends what you mean by 'valid RDF'. N3 obviously has a lot of syntax that goes way beyond what is legal in RDF, so its not valid RDF. But if you mean, the basic RDF semantics can be extended to cover all the constructs in N3 (without completely breaking) then yes, it can. In fact, N3 is a subset of Common Logic, and the same basic semantic construction of RDF works for all of CL. But it would be a real extension, in that all the 'extra' syntax of N3 (notably, the graph literals idea) would need to have its semantics specified explicitly. It wouldn't come for free. Hope I've answered your question (?) Pat ty so far, nathan IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola(850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Pat Hayes wrote: On Jul 2, 2010, at 12:07 AM, Nathan wrote: Pat Hayes wrote: On Jul 1, 2010, at 11:49 PM, Nathan wrote: Pat Hayes wrote: On Jul 1, 2010, at 11:18 AM, Yves Raimond wrote: A literal may be the object of an RDF statement, but not the subject or the predicate. Just to clarify, this is a purely syntactic restriction. Allowing literals in subject position would require **no change at all** to the RDF semantics. (The non-normative inference rules for RDF and RDFS and D-entailment given in the semantics document would need revision, but they would then be simplified.) I have to wonder then, what can one all place in the s,p,o slots without changing the RDF semantics? literal and bnode predicates for instance? variables or formulae as in n3? read as: if a new serialization/syntax was defined for RDF what are the limitations for the values of node/object and relationship specified by the RDF Semantics? None at all. The semantics as stated works fine with triples which have any kind of syntactic node in any position in any combination. The same basic semantic construction is used in ISO Common Logic, which allows complete syntactic freedom, so that the the same name can denote an individual, a property, a function and a proposition all at the same time. Pat PS. Its not a dumb question :-) thus is N3 valid RDF? (I read yes, but want/need to hear that's right!) Well, no. It depends what you mean by 'valid RDF'. N3 obviously has a lot of syntax that goes way beyond what is legal in RDF, so its not valid RDF. But if you mean, the basic RDF semantics can be extended to cover all the constructs in N3 (without completely breaking) then yes, it can. In fact, N3 is a subset of Common Logic, and the same basic semantic construction of RDF works for all of CL. But it would be a real extension, in that all the 'extra' syntax of N3 (notably, the graph literals idea) would need to have its semantics specified explicitly. It wouldn't come for free. Hope I've answered your question (?) perfectly, thanks!
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just about
impossible to guarantee that messes can't happen when all you are
doing is describing structures in an open-world setting. But I think
the cure is to stop thinking that possible-messes are a problem to be
solved. So, there is dung in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad 'linked
data' practise by using examples like { 'London' a x:Place } - whereas
I'd immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered with
'walk round it', and further good practise could be aided by a few
simple notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
Best,
Nathan
--
Regards,
Kingsley Idehen
President CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jun 30, 2010, at 11:50 AM, Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however it
is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just
about impossible to guarantee that messes can't happen when all you
are doing is describing structures in an open-world setting. But I
think the cure is to stop thinking that possible-messes are a
problem to be solved. So, there is dung in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad 'linked
data' practise by using examples like { 'London' a x:Place } -
whereas I'd immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered
with 'walk round it', and further good practise could be aided by a
few simple notes on best practise for linked data etc.
I wholly agree. Allowing literals in subject position in RDF is a no-
brainer. (BTW, it would also immediately solve the 'bugs in the RDF
rules' problem.) These arguments against it are nonsensical. The REAL
argument against it is that it will mess up OWL-DL, or at any rate it
*might* mess up OWL-DL.
The Description Logic police are still in charge:-)
Pat
Best,
Nathan
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
Pensacola(850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however
it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just
about impossible to guarantee that messes can't happen when all
you are doing is describing structures in an open-world setting.
But I think the cure is to stop thinking that possible-messes are
a problem to be solved. So, there is dung in the road. Walk round
it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad 'linked
data' practise by using examples like { 'London' a x:Place } -
whereas I'd immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered
with 'walk round it', and further good practise could be aided by a
few simple notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects
have Identifiers in the form of Name References (which may or many
resolve to Structured Representations of Referents carried or borne
by Descriptor Docs/Resources). An Identifier != Literal.
What ARE you talking about? You sound like someone reciting doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as URIs are.
They identify their value, most clearly and emphatically. They denote
in exactly the same way that URIs denote. 23^^xsd:number is about
as good an identification of the number twenty-three as you are ever
likely to get in any notational system since ancient Babylonia.
Pat Hayes
If you are in a situation where you can't or don't want to mint an
HTTP based Name, simply use a URN, it does the job.
Best,
Nathan
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
Pensacola(850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On 06/30/2010 09:09 PM, Pat Hayes wrote:
On Jun 30, 2010, at 11:50 AM, Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just about
impossible to guarantee that messes can't happen when all you are
doing is describing structures in an open-world setting. But I think
the cure is to stop thinking that possible-messes are a problem to be
solved. So, there is dung in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad 'linked
data' practise by using examples like { 'London' a x:Place } - whereas
I'd immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered with
'walk round it', and further good practise could be aided by a few
simple notes on best practise for linked data etc.
I wholly agree. Allowing literals in subject position in RDF is a
no-brainer. (BTW, it would also immediately solve the 'bugs in the RDF
rules' problem.) These arguments against it are nonsensical. The REAL
argument against it is that it will mess up OWL-DL, or at any rate it
*might* mess up OWL-DL.
I wonder, when using owl:sameAs or related, to name literals to be
able to say other useful thing about them in normal triples (datatype,
language, etc) does it break OWL DL (or any other formalism which is
base of some ontology extending RDF semantics)? Or would it if
rdf:sameAs was introduced?
Best,
Jiri
The Description Logic police are still in charge:-)
Pat
Best,
Nathan
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
Pensacola(850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
signature.asc
Description: OpenPGP digital signature
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On 30 June 2010 21:14, Pat Hayes pha...@ihmc.us wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using pointers,
which is what the RDF vocabulary describes. Its just about impossible to
guarantee that messes can't happen when all you are doing is describing
structures in an open-world setting. But I think the cure is to stop
thinking that possible-messes are a problem to be solved. So, there is dung
in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general discussion
that's going on then?
For example I've heard people saying that it encourages bad 'linked data'
practise by using examples like { 'London' a x:Place } - whereas I'd
immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered with
'walk round it', and further good practise could be aided by a few simple
notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
What ARE you talking about? You sound like someone reciting doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as URIs are. They
identify their value, most clearly and emphatically. They denote in exactly
the same way that URIs denote. 23^^xsd:number is about as good an
identification of the number twenty-three as you are ever likely to get in
any notational system since ancient Babylonia.
You can also do this:
http://km.aifb.kit.edu/projects/numbers/web/n23
Pat Hayes
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
Best,
Nathan
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog:
http://www.openlinksw.com/blog/~kidehenhttp://www.openlinksw.com/blog/%7Ekidehen
Twitter/Identi.ca: kidehen
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
Pensacola(850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Wed, 2010-06-30 at 14:09 -0500, Pat Hayes wrote: On Jun 30, 2010, at 11:50 AM, Nathan wrote: [ . . . ] Surely all of the subjects as literals arguments can be countered with 'walk round it', and further good practise could be aided by a few simple notes on best practise for linked data etc. I wholly agree. Allowing literals in subject position in RDF is a no- brainer. I agree, but at the W3C RDF Next Steps workshop over the weekend, I was surprised to find that there was substantial sentiment *against* having literals as subjects. A straw poll showed that of those at the workshop, this is how people felt about having an RDF working group charter include literals as subjects: http://www.w3.org/2010/06/28-rdfn-minutes.html Charter MUST include: 0 Charter SHOULD include:1 Charter MAY include: 6 Charter MUST NOT include: 12 Readers, please note that this was a non-binding, informative STRAW POLL ONLY -- not a vote. Pat, I wish you had been there. ;) David (BTW, it would also immediately solve the 'bugs in the RDF rules' problem.) These arguments against it are nonsensical. The REAL argument against it is that it will mess up OWL-DL, or at any rate it *might* mess up OWL-DL. The Description Logic police are still in charge:-) Pat Best, Nathan IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola(850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes -- David Booth, Ph.D. Cleveland Clinic (contractor) http://dbooth.org/ Opinions expressed herein are those of the author and do not necessarily reflect those of Cleveland Clinic.
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Intuitively, I would expect each subject literal to have a unique identity. For example, I would want to annotate a particular instance of abc and not all literals abc. Wouldn't the latter treatment make literals-as-subjects less appealing? Re. the DL police: I use RDF like a next-generation relational database and think that RDF could be sold to many people this way (there is possibly are larger audience for this than for ontologies, reasoning, etc.). Especially considering how No-SQL is currently taking off. This part needs some love and seems to suffer from the almost exclusive focus on semantics. Axel On Jun 30, 2010, at 21:52 , David Booth wrote: On Wed, 2010-06-30 at 14:09 -0500, Pat Hayes wrote: On Jun 30, 2010, at 11:50 AM, Nathan wrote: [ . . . ] Surely all of the subjects as literals arguments can be countered with 'walk round it', and further good practise could be aided by a few simple notes on best practise for linked data etc. I wholly agree. Allowing literals in subject position in RDF is a no- brainer. I agree, but at the W3C RDF Next Steps workshop over the weekend, I was surprised to find that there was substantial sentiment *against* having literals as subjects. A straw poll showed that of those at the workshop, this is how people felt about having an RDF working group charter include literals as subjects: http://www.w3.org/2010/06/28-rdfn-minutes.html Charter MUST include: 0 Charter SHOULD include:1 Charter MAY include: 6 Charter MUST NOT include: 12 Readers, please note that this was a non-binding, informative STRAW POLL ONLY -- not a vote. Pat, I wish you had been there. ;) David (BTW, it would also immediately solve the 'bugs in the RDF rules' problem.) These arguments against it are nonsensical. The REAL argument against it is that it will mess up OWL-DL, or at any rate it *might* mess up OWL-DL. The Description Logic police are still in charge:-) Pat Best, Nathan IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola(850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes -- David Booth, Ph.D. Cleveland Clinic (contractor) http://dbooth.org/ Opinions expressed herein are those of the author and do not necessarily reflect those of Cleveland Clinic. -- Dr. Axel Rauschmayer axel.rauschma...@ifi.lmu.de http://hypergraphs.de/ :: Hyena: connected information manager, free at hypergraphs.de/hyena/ ::
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
David Booth wrote: I agree, but at the W3C RDF Next Steps workshop over the weekend, I was surprised to find that there was substantial sentiment *against* having literals as subjects. A straw poll showed that of those at the workshop, this is how people felt about having an RDF working group charter include literals as subjects: http://www.w3.org/2010/06/28-rdfn-minutes.html Charter MUST include: 0 Charter SHOULD include:1 Charter MAY include: 6 Charter MUST NOT include: 12 I was one of the MUST NOTs to my surprise. Here are the reasons I voted this way: - it will mess up RDF/XML - RDF/XML is horrid but we had consensus that it was unfixable - i.e. we need to live with it. - however little work the WG does is too much in terms of the real obstacles to SW success (following Dan from http://lists.w3.org/Archives/Public/semantic-web/2010Mar/0196.html [[ What I feel is missing (despite the *millions*) that has been thrown at the Semantic Web brand, is the boring slog of getting the base tools and software polished. ]] ). In particular my view is that literals as subjects is not part of the problem to be solved. - this is a purists' desire not a practical obstacle. No value-adding argument made for a change of this magnitude. It's a bug. Fixing it may cost $0.5M to $1M say, maybe more. I don't see that much return. Jeremy
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just about
impossible to guarantee that messes can't happen when all you are
doing is describing structures in an open-world setting. But I think
the cure is to stop thinking that possible-messes are a problem to be
solved. So, there is dung in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad 'linked
data' practise by using examples like { 'London' a x:Place } - whereas
I'd immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered with
'walk round it', and further good practise could be aided by a few
simple notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects have
Identifiers in the form of Name References (which may or many resolve to
Structured Representations of Referents carried or borne by Descriptor
Docs/Resources). An Identifier != Literal.
If you are in a situation where you can't or don't want to mint an HTTP
based Name, simply use a URN, it does the job.
Surely that's Linked Data or a variant of EAV, not RDF - why should the
core level data model be restricted so that it can't be used to say
simple things like { 1 x:lessThan 2 ) ?
Moreover, { :a :b something } == { something [owl:inverseOf :b] :a }
aside: you know I fully grok all the benefits of linked data and am a
huge proponent, but rdf at it's core isn't linked data and saying:
{ x:London rdfs:label London }
is the same as saying
{ London is rdfs:label of x:London }
afaik, directionality doesn't come in to it.
Best,
Nathan
please do correct me if I'm wrong
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Pat Hayes wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just
about impossible to guarantee that messes can't happen when all you
are doing is describing structures in an open-world setting. But I
think the cure is to stop thinking that possible-messes are a
problem to be solved. So, there is dung in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad 'linked
data' practise by using examples like { 'London' a x:Place } -
whereas I'd immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered
with 'walk round it', and further good practise could be aided by a
few simple notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects
have Identifiers in the form of Name References (which may or many
resolve to Structured Representations of Referents carried or borne
by Descriptor Docs/Resources). An Identifier != Literal.
What ARE you talking about? You sound like someone reciting doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as URIs are.
They identify their value, most clearly and emphatically. They denote
in exactly the same way that URIs denote. 23^^xsd:number is about
as good an identification of the number twenty-three as you are ever
likely to get in any notational system since ancient Babylonia.
Yes, but ancient Bablyonia != World Wide Web of Structured Linked Data,
slightly different mediums with some shared characteristics :-)
The World Wide Web is becoming a Distributed DBMS (in my eyes). Thus,
unambiguous naming matters.
Literal Subjects aren't a show stopper per se. (esp. for local RDF
data). My gripe simply boils down to the nuisance factor introduced by
data object name ambiguity in a distributed data object oriented realm
such as the emerging Web of Linked Data.
What does 23^^xsd:number mean to anyone in a global data space? I
know the meaning of:
http://km.aifb.kit.edu/projects/numbers/web/n23#this, based on the
resource I deref at: http://km.aifb.kit.edu/projects/numbers/web/n23
Kingsley
Pat Hayes
If you are in a situation where you can't or don't want to mint an
HTTP based Name, simply use a URN, it does the job.
Best,
Nathan
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
Pensacola(850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
--
Regards,
Kingsley Idehen
President CEO
OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Pat Hayes wrote:
On Jun 30, 2010, at 11:50 AM, Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however it is
called) claims could probably make a mess, if added or removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just about
impossible to guarantee that messes can't happen when all you are
doing is describing structures in an open-world setting. But I think
the cure is to stop thinking that possible-messes are a problem to be
solved. So, there is dung in the road. Walk round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad 'linked
data' practise by using examples like { 'London' a x:Place } - whereas
I'd immediately counter with { x:London a 'Place' }.
Surely all of the subjects as literals arguments can be countered with
'walk round it', and further good practise could be aided by a few
simple notes on best practise for linked data etc.
I wholly agree. Allowing literals in subject position in RDF is a
no-brainer. (BTW, it would also immediately solve the 'bugs in the RDF
rules' problem.) These arguments against it are nonsensical. The REAL
argument against it is that it will mess up OWL-DL, or at any rate it
*might* mess up OWL-DL.
The Description Logic police are still in charge:-)
As you know I'm pretty new to this, relatively, but here's a thought I
can't get rid of.
Keep RDF as loose as possible at the core semantic level (subjects as
literals etc).
Have the semantics of each triple defined by it's predicate (each
property can define it's own domain and range etc)
This may also allow for using rdf as a data model, and there's no reason
every triple must be dereferencable etc.
Above this, afaict, no reason why each serialization can't have it's own
strong semantics too, like HTML+RDFa can instruct that a URI should be
embedded and so forth (img src=).
Just a thought.. I'm sure you can tell me why I'm wrong
re OWL DL, does it have to consider every triple in a 'graph'?
Nathan
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Wed, 30 Jun 2010 13:18:25 -0700 Jeremy Carroll jer...@topquadrant.com wrote: Here are the reasons I voted this way: - it will mess up RDF/XML No it won't - it will just mean that RDF/XML is only capable of representing a subset of RDF graphs. And guess what? That's already the case. -- Toby A Inkster mailto:m...@tobyinkster.co.uk http://tobyinkster.co.uk
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Toby Inkster wrote: On Wed, 30 Jun 2010 13:18:25 -0700 Jeremy Carroll jer...@topquadrant.com wrote: Here are the reasons I voted this way: - it will mess up RDF/XML No it won't - it will just mean that RDF/XML is only capable of representing a subset of RDF graphs. And guess what? That's already the case. Yes! +100 we all keep saying RDF isn't RDF/XML don't we..? Perhaps, RDF is really N3, with N3 Rules etc which expand it, and then different serializations support subsets of that - the RDF/XML spec already appears to be only a spec for RDF/XML not RDF (broadly speaking) maybe it just needs that said in a normative way so we can get on and build what we all really need, define a core RDF non serialization specific Rec/Spec then go from there - nobody says each serialization *must* handle all of RDF, but perhaps levels of conformance could be added to each serialization spec - has graph literals/formulae/nested graphs Y/N - has literal subjects y/n - supports rules y/n etc Best, Nathan
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Jiří Procházka wrote: I wonder, when using owl:sameAs or related, to name literals to be able to say other useful thing about them in normal triples (datatype, language, etc) does it break OWL DL yes it does (or any other formalism which is base of some ontology extending RDF semantics)? Not OWL full Or would it if rdf:sameAs was introduced? It would still break OWL DL Best, Jiri OWL DL is orthogonal to this issue. The OWL DLers already prohibit certain RDF - specifically the workaround for not having literal as subjects. So they are neutral. I reiterate that I agree whole-heartedly with the technical arguments for making this change; however the economic case is missing. Jeremy
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
Jeremy Carroll wrote: Jiří Procházka wrote: I wonder, when using owl:sameAs or related, to name literals to be able to say other useful thing about them in normal triples (datatype, language, etc) does it break OWL DL yes it does (or any other formalism which is base of some ontology extending RDF semantics)? Not OWL full Or would it if rdf:sameAs was introduced? It would still break OWL DL Best, Jiri OWL DL is orthogonal to this issue. The OWL DLers already prohibit certain RDF - specifically the workaround for not having literal as subjects. So they are neutral. I reiterate that I agree whole-heartedly with the technical arguments for making this change; however the economic case is missing. Are you referring to the cost of fixing RDF/XML or the cost of specifying RDF correctly and having RDF/XML as a subset of RDF? IMHO the economic case (and ethical, technical) is extremely strong when you look at it on the ten year timeline - pinning all of RDF on the serialization specific features and limitations of RDF/XML really hinders progress (now and in the future). There doesn't need to be any cost here, define RDF properly and separate from any serialization, define RDF/XML as a subset of it, and let us all get on and create new and wonderful serializations that will drive another decade of innovation. I'm 100% sure that if tooling for N3 was more widely available and the web of data was N3 powered, we'd be much further down the line - the proof is already there with the work done at MIT-CSAIL and RPI, fact is you simply can't do everything needed for a web of data with RDF/XML. Best, Nathan
RE: Subjects as Literals, [was Re: The Ordered List Ontology]
Jirí Procházka wrote: I wonder, when using owl:sameAs or related, to name literals to be able to say other useful thing about them in normal triples (datatype, language, etc) does it break OWL DL Literals in owl:sameAs axioms are not allowed in OWL (1/2) DL. owl:sameAs can only be used to equate individuals. An axiom of the form ex:u owl:sameAs foo . would, however, equate an individual with a data value. The semantics of OWL DL states that individuals and data values are disjoint [1], so such a statement would always lead to semantic inconsistency. But, in fact, the syntax of OWL DL disallows stating such an axiom, anyway: only URIs are allowed in sameness axioms [2]. (or any other formalism OWL Full allows it, both syntactically and semantically. which is base of some ontology extending RDF semantics)? OWL Full is an extension of the RDF Semantics in the sense of [3]. This explains why OWL Full can treat sameAs'ed literals semantically without problems: under the semantics of RDFS all data values are individuals (rdfs:Literal rdfs:subClassOf rdfs:Resource). So there is no disjointness between data values and individuals as in OWL DL. Also, as for RDFS, OWL Full allows for arbitrary RDF as input, so sameAs'ed literals are also syntactically allowed. Or would it if rdf:sameAs was introduced? Such a definition would probably not be different from what OWL Full already provides, only at a different semantic layer. So I would consider it redundant in RDF. Michael [1] http://www.w3.org/TR/2009/REC-owl2-direct-semantics-20091027/#Interpretation s [2] http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Individual_Equality [3] http://www.w3.org/TR/rdf-mt/#DefSemanticExtension -- Dipl.-Inform. Michael Schneider Research Scientist, Information Process Engineering (IPE) Tel : +49-721-9654-726 Fax : +49-721-9654-727 Email: michael.schnei...@fzi.de WWW : http://www.fzi.de/michael.schneider === FZI Forschungszentrum Informatik an der Universität Karlsruhe Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe Tel.: +49-721-9654-0, Fax: +49-721-9654-959 Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael Flor, Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus ===
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jun 30, 2010, at 2:52 PM, David Booth wrote: On Wed, 2010-06-30 at 14:09 -0500, Pat Hayes wrote: On Jun 30, 2010, at 11:50 AM, Nathan wrote: [ . . . ] Surely all of the subjects as literals arguments can be countered with 'walk round it', and further good practise could be aided by a few simple notes on best practise for linked data etc. I wholly agree. Allowing literals in subject position in RDF is a no- brainer. I agree, but at the W3C RDF Next Steps workshop over the weekend, I was surprised to find that there was substantial sentiment *against* having literals as subjects. A straw poll showed that of those at the workshop, this is how people felt about having an RDF working group charter include literals as subjects: http://www.w3.org/2010/06/28-rdfn-minutes.html Charter MUST include: 0 Charter SHOULD include:1 Charter MAY include: 6 Charter MUST NOT include: 12 Readers, please note that this was a non-binding, informative STRAW POLL ONLY -- not a vote. Pat, I wish you had been there. ;) I have very mixed views on this, I have to say. Part of me wanted badly to be present. But after reading the results of the straw poll, part of me wants to completely forget about RDF, never think about an ontology or a logic ever again, and go off and do something completely different, like art or philosophy. Pat David (BTW, it would also immediately solve the 'bugs in the RDF rules' problem.) These arguments against it are nonsensical. The REAL argument against it is that it will mess up OWL-DL, or at any rate it *might* mess up OWL-DL. The Description Logic police are still in charge:-) Pat Best, Nathan IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola(850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes -- David Booth, Ph.D. Cleveland Clinic (contractor) http://dbooth.org/ Opinions expressed herein are those of the author and do not necessarily reflect those of Cleveland Clinic. IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola(850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jun 30, 2010, at 3:49 PM, Kingsley Idehen wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 1:30 PM, Kingsley Idehen wrote:
Nathan wrote:
Pat Hayes wrote:
On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
On Wed, 30 Jun 2010 10:54:20 +0100
Dan Brickley dan...@danbri.org wrote:
That said, i'm sure sameAs and differentIndividual (or however
it is
called) claims could probably make a mess, if added or
removed...
You can create some pretty awesome messes even without OWL:
# An rdf:List that loops around...
#mylist a rdf:List ;
rdf:first #Alice ;
rdf:next #mylist .
# A looping, branching mess...
#anotherlist a rdf:List ;
rdf:first #anotherlist ;
rdf:next #anotherlist .
They might be messy, but they are *possible* structures using
pointers, which is what the RDF vocabulary describes. Its just
about impossible to guarantee that messes can't happen when all
you are doing is describing structures in an open-world setting.
But I think the cure is to stop thinking that possible-messes
are a problem to be solved. So, there is dung in the road. Walk
round it.
Could we also apply that to the 'subjects as literals' general
discussion that's going on then?
For example I've heard people saying that it encourages bad
'linked data' practise by using examples like { 'London' a
x:Place } - whereas I'd immediately counter with { x:London a
'Place' }.
Surely all of the subjects as literals arguments can be countered
with 'walk round it', and further good practise could be aided by
a few simple notes on best practise for linked data etc.
IMHO an emphatic NO.
RDF is about constructing structured descriptions where Subjects
have Identifiers in the form of Name References (which may or many
resolve to Structured Representations of Referents carried or
borne by Descriptor Docs/Resources). An Identifier != Literal.
What ARE you talking about? You sound like someone reciting doctrine.
Literals in RDF are just as much 'identifiers' or 'names' as URIs
are. They identify their value, most clearly and emphatically. They
denote in exactly the same way that URIs denote. 23^^xsd:number
is about as good an identification of the number twenty-three as
you are ever likely to get in any notational system since ancient
Babylonia.
Yes, but ancient Bablyonia != World Wide Web of Structured Linked
Data, slightly different mediums with some shared characteristics :-)
The World Wide Web is becoming a Distributed DBMS (in my eyes).
Thus, unambiguous naming matters.
A topic for a longer discussion; but irrelevant here, since typed
literals are as unambiguous as a name can possibly get.
Literal Subjects aren't a show stopper per se. (esp. for local RDF
data). My gripe simply boils down to the nuisance factor introduced
by data object name ambiguity in a distributed data object oriented
realm such as the emerging Web of Linked Data.
What does 23^^xsd:number mean to anyone in a global data space?
It means the number twenty-three, everywhere and for all time, because
this meaning can be computed from the very syntactic form of the name.
How unambiguous can something get?
Pat
I know the meaning of: http://km.aifb.kit.edu/projects/numbers/web/n23#this
, based on the resource I deref at: http://km.aifb.kit.edu/projects/numbers/web/n23
Kingsley
Pat Hayes
If you are in a situation where you can't or don't want to mint an
HTTP based Name, simply use a URN, it does the job.
Best,
Nathan
--
Regards,
Kingsley Idehen President CEO OpenLink Software
Web: http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
IHMC (850)434 8903 or (650)494
3973
40 South Alcaniz St. (850)202 4416 office
Pensacola(850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
--
Regards,
Kingsley Idehen President CEO OpenLink Software Web:
http://www.openlinksw.com
Weblog: http://www.openlinksw.com/blog/~kidehen
Twitter/Identi.ca: kidehen
IHMC (850)434 8903 or (650)494 3973
40 South Alcaniz St. (850)202 4416 office
Pensacola(850)202 4440 fax
FL 32502 (850)291 0667 mobile
phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jun 30, 2010, at 4:25 PM, Toby Inkster wrote: On Wed, 30 Jun 2010 13:18:25 -0700 Jeremy Carroll jer...@topquadrant.com wrote: Here are the reasons I voted this way: - it will mess up RDF/XML No it won't - it will just mean that RDF/XML is only capable of representing a subset of RDF graphs. And guess what? That's already the case. EXACTLY. Pat -- Toby A Inkster mailto:m...@tobyinkster.co.uk http://tobyinkster.co.uk IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola(850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Re: Subjects as Literals, [was Re: The Ordered List Ontology]
On Jun 30, 2010, at 3:12 PM, Axel Rauschmayer wrote: Intuitively, I would expect each subject literal to have a unique identity. For example, I would want to annotate a particular instance of abc and not all literals abc. Wouldn't the latter treatment make literals-as-subjects less appealing? Hmm. Im not sure what this means. Each literal has its own identity, in a sense, but what the literal refers to is the same in each case: every occurrence of 23^^xsd:number must refer to twenty-three. And since this (the number, not the literal) is what the literal refers to, and so what the RDF which uses the literal is talking about, why does it matter which literal you use to refer to it with? Maybe what you really need to do is to reify the literal and then talk about that. Then your notion of this literal vs. that literal does make sense, but it bears on the semantics of reification in RDF (or whatever finally takes its place in some future incarnation.) Re. the DL police: I use RDF like a next-generation relational database and think that RDF could be sold to many people this way (there is possibly are larger audience for this than for ontologies, reasoning, etc.). Especially considering how No-SQL is currently taking off. This part needs some love and seems to suffer from the almost exclusive focus on semantics. Fair enough. I guess Im not sure how this next-generation-RDB usage fits with the RDF semantics, but I'd be interested in pursuing this further. Does this RDF/RDB++ vision provide any guidance towards what RDF is supposed to, like, mean? Pointers? Pat Hayes Axel On Jun 30, 2010, at 21:52 , David Booth wrote: On Wed, 2010-06-30 at 14:09 -0500, Pat Hayes wrote: On Jun 30, 2010, at 11:50 AM, Nathan wrote: [ . . . ] Surely all of the subjects as literals arguments can be countered with 'walk round it', and further good practise could be aided by a few simple notes on best practise for linked data etc. I wholly agree. Allowing literals in subject position in RDF is a no- brainer. I agree, but at the W3C RDF Next Steps workshop over the weekend, I was surprised to find that there was substantial sentiment *against* having literals as subjects. A straw poll showed that of those at the workshop, this is how people felt about having an RDF working group charter include literals as subjects: http://www.w3.org/2010/06/28-rdfn-minutes.html Charter MUST include: 0 Charter SHOULD include:1 Charter MAY include: 6 Charter MUST NOT include: 12 Readers, please note that this was a non-binding, informative STRAW POLL ONLY -- not a vote. Pat, I wish you had been there. ;) David (BTW, it would also immediately solve the 'bugs in the RDF rules' problem.) These arguments against it are nonsensical. The REAL argument against it is that it will mess up OWL-DL, or at any rate it *might* mess up OWL-DL. The Description Logic police are still in charge:-) Pat Best, Nathan IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola(850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes -- David Booth, Ph.D. Cleveland Clinic (contractor) http://dbooth.org/ Opinions expressed herein are those of the author and do not necessarily reflect those of Cleveland Clinic. -- Dr. Axel Rauschmayer axel.rauschma...@ifi.lmu.de http://hypergraphs.de/ :: Hyena: connected information manager, free at hypergraphs.de/ hyena/ :: IHMC (850)434 8903 or (650)494 3973 40 South Alcaniz St. (850)202 4416 office Pensacola(850)202 4440 fax FL 32502 (850)291 0667 mobile phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
