This mentions empty strings but doesn't give an example of one:
*Lexical Space.* An rdf:PlainLiteral lexical form is a string of the
form "/abc/@/langTag/" where "/abc/" is an arbitrary (possibly empty)
string, and "/langTag/" is either the empty string or a (not necessarily
lowercase) language tag. Each such lexical form is mapped to a data
value dv as follows:
* If "/langTag/" is empty, then dv is equal to the string "/abc/" and
* If "/langTag/" is not empty, then dv is equal to the pair <"/abc/",
"/lc-langtag/" > where "/lc-langtag/" is "/langTag/" normalized to
lowercase.
[http://www.w3.org/TR/rdf-plain-literal/]
I'm assuming it would be "". Do you think that works?
rdf:nil seems to be only for lists.
"5.2.4 rdf:nil
The resource |rdf:nil| is an instance of |rdf:List
<http://www.w3.org/TR/rdf-schema/#ch_list>| that can be used to
represent an empty list or other list-like structure."
[http://www.w3.org/TR/rdf-schema/#ch_nil]
And I think I might be further along in this thinking if I could
understand this discussion:
http://milicicvuk.com/blog/2011/07/16/problems-of-the-rdf-model-literals/
The fact that much of library data consists of literals is an issue, and
I don't (yet) understand what that means in terms of RDF. Sometimes I
think that we should be treating our bibliographic descriptions as
documents with RDF/RDFa markup where appropriate, rather than pretending
that all of these strings are data. Sometimes I don't think that. ;-)
kc
On 9/14/13 9:06 AM, Esmé Cowles wrote:
Yes, I was thinking you would create a content as text node, and just leave the
value blank (or maybe use something like rdf:nil).
And the good thing about qnames is that you can use whatever you want. I always use "mads:" instead of
"madsrdf:" for MADS, and would use "cat:" or "content:" for content as text.
-Esme
--
Esme Cowles <escow...@ucsd.edu>
"Necessity is the plea for every infringement of human freedom. It is the
argument of tyrants; it is the creed of slaves." -- William Pitt, 1783
On 09/14/2013, at 10:27 AM, Karen Coyle <li...@kcoyle.net> wrote:
Hmm. For the missing title would you create a content as text node with a blank
body? How does RDF handle empty strings?!
(And I'm sorry to say that the qname for content as text is "cnt" - I'm going
to have to just get over the dis-ease that causes me )
kc
On 9/14/13 6:47 AM, Esmé Cowles wrote:
That looks like a nice way to handle many different cases where you have a
textual value, and may also want to attach other triples about certainty,
source, definiteness, etc. This would neatly handle the missing or definitely
non-existent title problem. And it also avoids sub-optimal approaches like
reification or having to create a new class for every possible value that you
might want to annotate.
-Esme
--
Esme Cowles <escow...@ucsd.edu>
"Necessity is the plea for every infringement of human freedom. It is the
argument of tyrants; it is the creed of slaves." -- William Pitt, 1783
On 09/14/2013, at 9:02 AM, Karen Coyle <li...@kcoyle.net> wrote:
This reminds me of a conversation (that did not come to a conclusion) on the
BIBFRAME list about the need to have a way to say that a bit of data is
transcribed, not transcribed, or supplied. And that reminds me of the issues
with SKOS labels, which is that if your data is text, not a URI, you can't say
anything further about that because text cannot be the subject of a triple. And
this was also the issue between BIBFRAME and Open Annotation because BIBFRAME
wanted to have annotations that are plain text, and Open Annotation doesn't
allow that for the reason that you can't further describe the text.
Which leads me to conclude that we would need to be using Content as Text
http://www.w3.org/TR/Content-in-RDF10/#ContentAsTextClass
kc
On 9/13/13 8:57 AM, Stephen Hearn wrote:
The MARC21 Authority format does have some negative assertions. Field 675
asserts that a source contains no relevant information (vs. 670 which
asserts the source and its relevant information). Field 673 asserts that a
title is not related to the entity in the 1XX (vs. 672 which asserts that
the two are related). These aren't yet mapped in any detail to RDF or to
MADS, but finding a way to map them could be a practical approach the
question of negative assertions.
Stephen
On Fri, Sep 13, 2013 at 9:12 AM, Karen Coyle <li...@kcoyle.net> wrote:
On 9/13/13 5:51 AM, Esmé Cowles wrote:
Thomas-
This isn't something I've run across yet. But one thing you could do is
create some URIs for different kinds of unknown/nonexistent titles:
example:book1 dc:title example:unknownTitle
example:book2 dc:title example:noTitle
etc.
I'm bothered by the semantics of this... but maybe I'm being too rigid.
This states that the title is a URI, not a string, and that the URI is a
status, not the actual title. Your system will have a mixture of literal
strings that ARE titles and URIs that say something about titles, both as
objects of dc:title. The object of DC title needs to be the title. The
title COULD be a URI if the URI represents the title (e.g. a uniform title
in an authority file).
Even if this turns out to be "legal" from an RDF point of view, it seems
that this would complicate title displays because you'd have to treat these
URIs differently from the usual title literals, which you could just grab
and toss into a display.
I'd probably leave title as the literal string, and create a new property
for title status that takes its value from a controlled list. In fact,
wouldn't we need something almost identical for anonymous works, to say
that there really isn't an author. (Cataloging knowledge lapse: we quit
using "Anonymous" as an author a while ago, right?) Given the open world
assumption, we are going to need to make these kinds of negative statements.
Also, remember that OWL does NOT constrain your data, it constrains only
the inferences that you can make about your data. OWL operates at the
ontology level, not the data level. (The OWL 2 documentation makes this
more clear, in my reading of it. I agree that the example you cite sure
looks like a constraint on the data... it's very confusing.)
This book has no title:
example:thisbook dc:title hasobject:false .
I don't think the title itself can be "hasobject:false". I think you need
to have a property like: xx:hasATitle and this can be true or false. But
I'm going to run this by the folks who developed dc in RDF and see what
they say. [Did so, they concur = value of title must be a title, not
information about title or status of title.]
Note that dcterms title is defined specifically as having a literal value:
Term Name: title
URI: http://purl.org/dc/terms/title
Label: Title
Definition: A name given to the resource.
Type of Term: Property <http://www.w3.org/1999/02/22-**
rdf-syntax-ns#Property<http://www.w3.org/1999/02/22-rdf-syntax-ns#Property>
Refines:
http://purl.org/dc/elements/1.**1/title<http://purl.org/dc/elements/1.1/title>
Version:
http://dublincore.org/usage/**terms/history/#titleT-002<http://dublincore.org/usage/terms/history/#titleT-002>
Has Range:
http://www.w3.org/2000/01/rdf-**schema#Literal<http://www.w3.org/2000/01/rdf-schema#Literal>
Whereas dc 1.1 (the old 15 element set) is more open:
URI:
http://purl.org/dc/elements/1.**1/title<http://purl.org/dc/elements/1.1/title>
Label: Title
Definition: A name given to the resource.
Type of Term: Property <http://www.w3.org/1999/02/22-**
rdf-syntax-ns#Property<http://www.w3.org/1999/02/22-rdf-syntax-ns#Property>
Version:
http://dublincore.org/usage/**terms/history/#title-006<http://dublincore.org/usage/terms/history/#title-006>
Note: A second property with the same name as this property has been
declared in the dcterms: namespace (http://purl.org/dc/terms/). See the
Introduction to the document "DCMI Metadata Terms" (http://dublincore.org/
**documents/dcmi-terms/ <http://dublincore.org/documents/dcmi-terms/>)
for an explanation.
I still think you are going outside of the definition of dc:title, which
is "The name of the resource." UNLESS you treat your "no title" as the
actual name of the resource, like "untitled" as the title of a painting.
But then we do have a serial with the actual title "Title varies" ... ;-)
kc
It is unknown if this book has a title (sounds undesirable but I can
think of instances where it might be handy[2]):
example:thisbook dc:title hasobject:unknown .
This book has a title but it has not been specified:
example:thisbook dc:title hasobject:true .
In terms of cataloguing, the answer is perhaps to refer to the rules
(which would normally mandate supplied titles in square brackets and so
forth) rather than use RDF to express this kind of thing, although the
rules differ depending on the part of description and, in the case of the
kind of thing that prompted the question- the presence of clasps on rare
books- there are no rules. I wonder if anyone has any more wisdom on this.
Many thanks,
Tom
[1] Adapted from http://www.w3.org/2007/OWL/**
wiki/Primer#Object_Properties<http://www.w3.org/2007/OWL/wiki/Primer#Object_Properties>
[2] No many tbh, but e.g. title in an unknown script or indecipherable
hand.
---
Thomas Meehan
Head of Current Cataloguing
Library Services
University College London
Gower Street
London WC1E 6BT
t.mee...@ucl.ac.uk
--
Karen Coyle
kco...@kcoyle.net http://kcoyle.net
ph: 1-510-540-7596
m: 1-510-435-8234
skype: kcoylenet
--
Karen Coyle
kco...@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet
--
Karen Coyle
kco...@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet
--
Karen Coyle
kco...@kcoyle.net http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet
