Re: canonicURI property

On 1/3/13 6:24 PM, Bernard Vatant wrote:
> Hi folks
>
> Sorry to differ with Kingsley on this, but this is an old trap :)
>
>     On 1/3/13 11:19 AM, SERVANT Francois-Paul wrote:
>
>
>         what property should be used to write in RDF links such as
>         those denoted by <link rel="canonical" href="…">? Is it
>         con:preferredURI?
>
>
> Although con:preferredURI is a priori dedicated to agents, I guess you 
> can extend its use to other resources, since the domain is left open 
> in this vocabulary. If the creator TBL is lurking, he can confirm his 
> intentions :)
>
>         Why is the object of con:preferredURI a string and not a resource?
>
>
> Because the preferred URI value is what it is : a URI, hence a 
> rdf:Literal, and not the resource named/identified by this literal
> con:preferredURI is a simple rdf:Property because contact vocabulary 
> is expressed in RDFS, but it's clear by its definition ...
>
>    <rdf:Property  rdf:about="http://www.w3.org/2000/10/swap/pim/contact#preferredURI">
>          <comment>A string which is the URI a person, organization, etc, prefers that people use for them.</comment>
>          <label>preferred</label>
>      </rdf:Property>
> ... that if this vocabulary were to be translated in OWL, it would 
> become a owl:DatatypeProperty with range xsd:anyURI
>
>         I have in a linked data set URIs in my namespace that are
>         owl:sameAs, and among them one which is a "canonical one".
>         When dereferencing one of these URIs, I want to state in the
>         returned RDF something like:
>         :OneOfThoseURIs x:canonicURI :TheCanonicOne.
>         and then have triples about :TheCanonicOne
>
>
> You can't do that, because  :TheCanonicOne is a rdf:Literal which 
> cannot be in subject position (so far ...)
>
>         My goal is to make clear that the preferredURI (the one that
>         should be used - and the one that actually is used in the
>         returned RDF) is :TheCanonicOne. Of course:
>
>         x:canonicURI rdfs:subPropertyOf owl:sameAs.
>
>
> Of course not! This is the trap. You confuse the URI (the string) with 
> the resource it identifies.
>
> What you mean is that all sameAs resources share the preferred URI. 
> For example
>
> IF
> :x  con:preferredURI  'myNiceURI'
>
> THEN
> ( :y  con:preferredURI  'myNiceURI'' ) <=> ( :y owl:sameAs  :x )
>
> A system can rely on the preferredURI value e.g., to use it as the 
> rdf:about value in a RDF/XML. But that's all. If you have owl:sameAs 
> declarations, all sameAs URIs would be equivalent in rdf:about with 
> the same semantics. preferredURI is akin to skos:prefLabel, no more, 
> no less.
>
> Best regards
>
> Bernard
>
>
> *Bernard Vatant
> *
> Vocabularies & Data Engineering
> Tel : + 33 (0)9 71 48 84 59
> Skype : bernard.vatant
> Blog : the wheel and the hub <http://blog.hubjects.com/>
>
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Yes, I stated:

:canonicalURI owl:equivalentProperty xhv:canonical;
    rdfs:subPropertyOf owl:sameAs.

## for good measure
xhv:canonical rdfs:subPropertyOf owl:sameAs .


Note, my instinctive thinking was:

x:canonicalURI :notOwlSameAs :canonicalURI .  :-)

So the question, as I now see it, is this:

What does xhv:canonical denote ?  Answer: a URI, an Identifier rather 
than an entity denoted by said Identifier.

Conclusion:

You are correct :-)

-- 

Regards,

Kingsley Idehen	
Founder & CEO
OpenLink Software
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