Re: OWL URI and namespace, an issue for LOV.

Hi Simon

Not sure I get your point. I know those documents of course, and BTW since
you mention it http://www.w3.org/2000/01/rdf-schema has not the bug
(feature) pointed for OWL, since it uses the namespace as the ontology URI,
thus :

<http://www.w3.org/2000/01/rdf-schema#> a owl:Ontology
rdfs:subClassOf a rdf:Property ;
    rdfs:isDefinedBy <http://www.w3.org/2000/01/rdf-schema#>

And since RDFS does it right (IMO) I wonder why OWL does otherwise. That is
the question.

Bernard



2014-06-17 16:59 GMT+02:00 Simon Spero <sesuncedu@gmail.com>:

> I think this is correct:
> http://www.w3.org/TR/cooluris/#linking
>
> But there's also this:
> http://www.w3.org/2000/01/rdf-schema
>
> On Jun 17, 2014 9:18 AM, "Bernard Vatant" <bernard.vatant@mondeca.com>
> wrote:
>
>> Hi all
>>
>> Sorry this looks like a permathread on namespaces and URIs, but hopefully
>> someday someone will come out with a definitive and convincing explanation
>> which will enlighten my old brain.
>>
>> We've been looking more closely in the OWL namespace publication, for
>> inclusion into LOV cloud [1]. We'd been reluctant so far to include RDF,
>> RDFS and OWL RDF schemas as ordinary LOV citizens, because of their
>> particular status, but we are now experimenting it, in order to capture
>> some information on how various vocabularies use RDFS or OWL, for example.
>> In LOV we have some pragmatic rules, which are as difficult to figure as
>> to enforce, to find out the vocabulary URI and the vocabulary namespace.
>> They can be the same, or quite the same (differing by a final # or /, for
>> example), or completely different. In the best of worlds, the vocabulary
>> URI and the vocabulary namespace dereference ultimately to the same RDF
>> file.
>> Sometimes, the vocabulary URI dereferences, but not the namespace (in
>> case of purl URIs, crazy things happen etc)
>>
>> We tend to trust what the vocabulary publisher declares, if it's
>> consistent. If the vocabulary RDF file contains one predicate (?uri a
>> owl:Ontology), and ?uri is dereferencing properly with or without conneg to
>> the said file, we take ?uri to be the vocabulary URI.
>> In the case of OWL either http://www.w3.org/2002/07/owl or
>> http://www.w3.org/2002/07/owl# dereference to the same Turtle file, in
>> which one can read :
>>
>> <http://www.w3.org/2002/07/owl> a owl:Ontology   (A1)
>>
>> So far so good. From the previous rule, we take
>> http://www.w3.org/2002/07/owl to be the vocabulary URI, and
>> http://www.w3.org/2002/07/owl# the associated namespace (defined in the
>> prefix declarations).
>>
>> But, in the OWL elements definition, we read e.g.,
>>
>> owl:Class a rdfs:Class ;
>>      rdfs:isDefinedBy <http://www.w3.org/2002/07/owl#>
>>
>> One would expect http://www.w3.org/2002/07/owl as the object of
>> rdfs:isDefinedBy, to be consistent with (A1) above.
>>
>> It figures :
>> - Are http://www.w3.org/2002/07/owl# and http://www.w3.org/2002/07/owl
>> equivalent URIs? IOW should a RDF application (e.g., the LOV-Bot) consider
>> them as the same resource?
>> - If no, what is the rationale of using one here and the other there?
>> - If yes ... same question :)
>>
>> In the current state of affairs, in LOV we add automatically in the
>> back-end triple store a triple
>> (?x  rdfs:isDefinedBy  ?uri) to every element ?x (class or property)
>> found in a vocabulary, with ?uri being the vocabulary URI as above defined.
>> Those triples add to the ones already declared in the vocabulary itself, if
>> any (most of the time there are no such declarations).
>>
>> In the OWL case we will eventually have in the triple store the two
>> following triples, one declared and the other one inferred :
>>
>> owl:Class rdfs:isDefinedBy <http://www.w3.org/2002/07/owl#>
>> owl:Class rdfs:isDefinedBy <http://www.w3.org/2002/07/owl>
>>
>> This is noisy at best. The question is : should LOV change its rules
>> regarding namespaces and URIs, or is the OWL schema broken?
>>
>> Thanks for your attention
>>
>> [1] http://lov.okfn.org/dataset/lov/details/vocabulary_owl.html
>> --
>>
>> *Bernard Vatant*
>> Vocabularies & Data Engineering
>> Tel :  + 33 (0)9 71 48 84 59
>>  Skype : bernard.vatant
>> http://google.com/+BernardVatant
>> --------------------------------------------------------
>> *Mondeca*
>> 35 boulevard de Strasbourg 75010 Paris
>> www.mondeca.com
>> Follow us on Twitter : @mondecanews <http://twitter.com/#%21/mondecanews>
>> ----------------------------------------------------------
>>
>


-- 

*Bernard Vatant*
Vocabularies & Data Engineering
Tel :  + 33 (0)9 71 48 84 59
Skype : bernard.vatant
http://google.com/+BernardVatant
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*Mondeca*
35 boulevard de Strasbourg 75010 Paris
www.mondeca.com
Follow us on Twitter : @mondecanews <http://twitter.com/#%21/mondecanews>
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