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Re: canonicURI property

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Fri, 4 Jan 2013 00:24:27 +0100
Message-ID: <CAK4ZFVFXq2CJy+auyM0KWo-=FY1qHXckv8k9sLybn5ua2oOLiA@mail.gmail.com>
To: SERVANT Francois-Paul <francois-paul.servant@renault.com>
Cc: public-lod@w3.org
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 ...

     <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

:x  con:preferredURI  'myNiceURI'

( :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 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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Received on Thursday, 3 January 2013 23:25:16 UTC

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