On 1/3/13 6:24 PM, Bernard Vatant wrote:
Hi folksSorry 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:anyURII 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 :TheCanonicOneYou 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 exampleIF :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/> -------------------------------------------------------- *Mondeca***** 3 cité Nollez 75018 Paris, France www.mondeca.com <http://www.mondeca.com/> Follow us on Twitter : @mondecanews <http://twitter.com/#%21/mondecanews>
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 Company Web: http://www.openlinksw.com Personal Weblog: http://www.openlinksw.com/blog/~kidehen Twitter/Identi.ca handle: @kidehen Google+ Profile: https://plus.google.com/112399767740508618350/about LinkedIn Profile: http://www.linkedin.com/in/kidehen
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