Yes, exactly. To simplify it even more:
There are graphs and they have identity - graph URI. owl:imports statements refer to the graph URIs. A graph contains a set of triple statements about some resources. These resources also have identity - URIs of resources. URIs are formed by combining some namespace with a local name. There is no requirement for the namespace used to form the URI of a graph to be the same as the namespace(s) used to form URIs of resources that participate in the triple statements in a graph. In many cases, it is a good practice for resources to use the same namespace as the graph - at least resources that are subjects in the triples contained in a graph. However, there are also significant exceptions and you can see examples of this all over the place. > On Apr 9, 2021, at 6:32 AM, David Price <[email protected]> wrote: > > Hi Michel, > > I > >> On 9 Apr 2021, at 09:52, 'Bohms, H.M. (Michel)' via TopBraid Suite Users >> <[email protected] <mailto:[email protected]>> >> wrote: >> >> Ok,….my misunderstanding becomes clearer…😊 >> >> Typically i used up till now owl:imports referencing other name spaces >> >> Do I understand now that the import can also be a (sub)graph/file saying >> something about a name space? >> >> If both rdfs and shacl variant have name space say https://w3id.org/nen2660 >> <https://w3id.org/nen2660>/def , what would the owl:imports statement look >> like in the shacl variant file? >> >> Guess I used up till now some assumptions on name space uri versus graph uri >> that I now better have to differentiate…. > > > I’ll simply a bit, but a good way to think about it is that the concept of > the named graph (with name being a Graph URI) is actually what owl:imports > references. A named graph may define classes/properties that use any number > of namespaces, made simpler by using prefixes for the namespaces. > > A named graph with Graph URI like https://w3id.org/nen2660/shapes > <https://w3id.org/nen2660/shapes> is not the same thing as a concept of > Namespace URI like https://w3id.org/nen2660# <https://w3id.org/nen2660#>. > From the Turtle Primer: > > prefix rdfs:, namespace URI: http://www.w3.org/2000/01/rdf-schema# > <http://www.w3.org/2000/01/rdf-schema#> > > Note that it calls the non-local name of a full URI a "namespace URI” so I > should probably be doing that too. > > Technically, there is zero relationship between the graph URI and namespace > URI. The named graph can be http://anything.at.all <http://anything.at.all/> > and define classes and properties using http://michel.com# > <http://michel.com/#> as the namespace URI. That much difference may confuse > people, so it’s not usually recommended but it’s fine technically. > > All the classes/properties of interest can then use the same namespace URI, > even if they are managed in different named graphs > > So, https://w3id.org/nen2660 <https://w3id.org/nen2660/Thing1>#Class1 > <https://w3id.org/nen2660/Thing1> an rdfs:Class can be in > https://w3id.org/nen2660/schema <https://w3id.org/nen2660/schema> graph and > https://w3id.org/nen2660 <https://w3id.org/nen2660/Thing2>#NodeShape2 > <https://w3id.org/nen2660/Thing2> a SHACL NodeShape can be in > https://w3id.org/nen2660/shapes <https://w3id.org/nen2660/shapes> graph. > > Both graphs as TTL would state > > @prefix nen2660: <https://w3id.org/nen2660# <https://w3id.org/nen2660#>> . > > so you’d see nen2660:Class1 and nen2660:NodeShape2 and so things are is > consistent wrt writing SPARQL queries, for example, over the schema/shapes > and over the data. > > Then https://w3id.org/nen2660/shapes <https://w3id.org/nen2660/shapes> > owl:imports https://w3id.org/nen2660/schema > <https://w3id.org/nen2660/schema> so NodeShape2 can refer to Class1. > > Tooling often supports a “Default Namespace” for a graph exactly to simplify > the separation of the Graph URI from the namespace URI. > > This separation also supports versions of ontologies. So, for example named > graphs http://standard.iso.org/mystandard/edition1 > <http://standard.iso.org/mystandard/edition1> and > http://standard.iso.org/mystandard/edition2 > <http://standard.iso.org/mystandard/edition2> > can both contain > > http://standard.iso.org/mystandard/ > <http://standard.iso.org/mystandard/MyClass>MyClass > <http://standard.iso.org/mystandard/MyClass> a rdfs:Class . > > with no problem. > > Cheers, > David > >> >> >> >> Dr. ir. H.M. (Michel) Bohms >> Scientist Specialist >> Structural Reliability >> T +31 (0)88 866 31 07 >> M +31 (0)63 038 12 20 >> E [email protected] <mailto:[email protected]> >> Location <http://www.tno.nl/locations/DTS> >> >> >> <image001.gif> <http://www.tno.nl/> >> This message may contain information that is not intended for you. If you >> are not the addressee or if this message was sent to you by mistake, you are >> requested to inform the sender and delete the message. TNO accepts no >> liability for the content of this e-mail, for the manner in which you use it >> and for damage of any kind resulting from the risks inherent to the >> electronic transmission of messages. >> >> Van: [email protected] >> <mailto:[email protected]> <[email protected] >> <mailto:[email protected]>> Namens Holger Knublauch >> Verzonden: vrijdag 9 april 2021 10:42 >> Aan: [email protected] <mailto:[email protected]> >> Onderwerp: Re: [topbraid-users] best practise name space in multiple >> languages? >> >> >> >> On 9/04/2021 6:31 pm, 'Bohms, H.M. (Michel)' via TopBraid Suite Users wrote: >> >> Dear Holger >> >> One more question on this. >> >> Indeed serialization is other dimension related to server negotiation etc. >> Skos variant is special: totally different beasts (instance versus class >> etc.) so indeed separate namespace/prefix (we dicided for rdfs:isDefinedBy >> to make links between them; in practice you see many other relations used). >> Lets focus on name spaces for rdfs/owl/shacl variants, let’s assume variant: >> owl & shacl both importing rdfs (not: shacl importing owl) >> Even more focus: rdfs & shacl only (forget about owl for now) >> Below you propose a different prefix/ns for the shacl-variant >> (nen2660-shacl). >> >> Now the question. Would it be somehow possible to use the same name space >> for both rdfs and shacl? >> (think you state that too below…) >> >> So having two files/graphs having the same name space, one stating the rdfs >> stuff, the other the shacl. >> Yes we do this in our EDG namespace, which is split across dozens of files, >> but they all declare resources from the edg: namespace. Namespaces and graph >> URIs are relatively separate topics, so any graph can declare resources from >> any namespace. >> >> >> Then I guess you need a mechanism to merge the two files/graphs other then >> owl:import (imports does not make sense since it is logical and the ontology >> would import itself)? >> I don't understand this argument - we use owl:imports between the edg: files >> without problems. >> >> Holger >> >> >> >> >> Thx again (for your patience…), >> michel >> >> >> >> >> Dr. ir. H.M. (Michel) Bohms >> Scientist Specialist >> Structural Reliability >> T +31 (0)88 866 31 07 >> M +31 (0)63 038 12 20 >> E [email protected] <mailto:[email protected]> >> Location <http://www.tno.nl/locations/DTS> >> >> >> <image001.gif> <http://www.tno.nl/> >> This message may contain information that is not intended for you. If you >> are not the addressee or if this message was sent to you by mistake, you are >> requested to inform the sender and delete the message. TNO accepts no >> liability for the content of this e-mail, for the manner in which you use it >> and for damage of any kind resulting from the risks inherent to the >> electronic transmission of messages. >> >> Van: [email protected] >> <mailto:[email protected]> <[email protected]> >> <mailto:[email protected]> Namens Holger Knublauch >> Verzonden: dinsdag 6 april 2021 13:22 >> Aan: [email protected] <mailto:[email protected]> >> Onderwerp: Re: [topbraid-users] best practise name space in multiple >> languages? >> >> Hi Michel, >> >> First we should make sure that the users of your models understand the >> distinction between namespaces and graph URIs. You can of course use the >> same namespace (e.g., https://w3id.org/def/nen2660# >> <https://w3id.org/def/nen2660>) in multiple graphs. What you are probably >> referring to is the Graph URI under which the models will be downloaded from >> on the Web. >> >> For the RDFS part, assuming this merely declares classes, properties and >> their relationships, I suggest they should be found at the URI that is like >> the namespace (except maybe without the #). Then, the OWL version could be >> at a URI ending with nen2660-owl and the SHACL version could be at >> nen2660-shacl, and both would have owl:imports statements to the RDFS Graph >> URI. OWL is typically pretty strict about what is allowed in the models, >> e.g. to preserve the OWL DL logic. On the other hand, SHACL is quite relaxed >> if a graph also contains OWL axioms - they will simply be ignored. So in >> theory the SHACL graph may owl:import the OWL version too. >> >> Using owl:imports will make sure that declarations are not repeated across >> files, and therefore don’t risk running out of sync, e.g. if someone changes >> the RDFS classes only in one file. >> >> I don’t know enough about how the SKOS version is different to comment on >> that. I would find it rather confusing if a resource is a class in one graph >> but a SKOS concept in another. >> >> The topic of RDF/XML vs Turtle etc is another dimension, typically solved >> using HTTP content negotiation. All serialisations would be accessible from >> the same server URLs yet the server would return different results depending >> on what accept header the client requests. >> >> Holger >> >> >> >> >> On 6 Apr 2021, at 6:20 pm, 'Bohms, H.M. (Michel)' via TopBraid Suite Users >> <[email protected] <mailto:[email protected]>> >> wrote: >> >> In case I have the same specification on different modelling levels: >> Skos >> Rdfs >> Rdfs+owl >> Rdfs+shacl >> >> Is there some best practice for the name space? >> >> (compare same name space for different serializations but now for different >> languages used…). >> >> I now have ie: >> >> # baseURI: https://w3id.org/def/nen2660-rdfs >> <https://w3id.org/def/nen2660-rdfs> >> >> But I got the comment that just: >> # baseURI: https://w3id.org/def/nen2660 <https://w3id.org/def/nen2660> >> >> was preferred. >> >> But then I have 4 variants (actually 12: all in rdf/xml, turtle and json-ld) >> specifying for the same name space. >> >> Thx for advice, >> Michel >> >> >> >> Dr. ir. H.M. (Michel) Bohms >> Scientist Specialist >> Structural Reliability >> T +31 (0)88 866 31 07 >> M +31 (0)63 038 12 20 >> E [email protected] <mailto:[email protected]> >> Location <http://www.tno.nl/locations/DTS> >> >> >> <image001.gif> <http://www.tno.nl/> >> This message may contain information that is not intended for you. If you >> are not the addressee or if this message was sent to you by mistake, you are >> requested to inform the sender and delete the message. 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