W3C home > Mailing lists > Public > public-lod@w3.org > January 2013

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 ...

  <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/>

--------------------------------------------------------
*Mondeca**          **                   *
3 cité Nollez 75018 Paris, France
www.mondeca.com
Follow us on Twitter : @mondecanews <http://twitter.com/#%21/mondecanews>
Received on Thursday, 3 January 2013 23:25:16 UTC

This archive was generated by hypermail 2.3.1 : Sunday, 31 March 2013 14:24:45 UTC