W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > June 2002

Re: refining closure text for rdfs-isDefinedBy-semantics

From: patrick hayes <phayes@ai.uwf.edu>
Date: Wed, 12 Jun 2002 12:35:36 -0500
Message-Id: <p05111a0bb92d330afcd9@[]>
To: Patrick Stickler <patrick.stickler@nokia.com>
Cc: w3c-rdfcore-wg@w3.org

>On 2002-06-11 10:29, "ext Patrick Stickler" <patrick.stickler@nokia.com>
>>  On 2002-06-10 19:01, "ext Eric Miller" <em@w3.org> wrote:
>>>  Now that i'm back online, I see Patrick's suggestion...
>>>  On Fri, 2002-06-07 at 11:15, Patrick Stickler wrote:
>>>>  My specific recommendations are:
>>>>  1. Leave the definition of rdfs:isDefinedBy as is, though removing
>>>>  the incorrect language about namespaces, allowing any instance
>>>>  of rdf:Resource and multiple statements.
>>>>  2. Qualify objects of rdfs:isDefinedBy by class, in the case of
>>>>  RDF/XML instances, by the proposed rdfs:Schema class. This permits
>>>>  those who want/need to, to be explicit about the nature of the
>>>>  defining resource.
>>>>  3. Clearly state that there is no functional relationship between
>>>>  the URI of a term and the namespace URI used in its RDF/XML
>>>>  serialization -- that the RDF model is based on URIs, not
>>>>  qnames, and as such, namespaces have no significance whatsoever.
>>>  yep, i believe we're saying similar things.
>>>  Patrick, have you taken a crack at this rewording?
>>  Not yet, but I would be happy to do so prior to Friday's telecon.
>Here goes:
><rdfs:Property rdf:about="&rdfs;isDefinedBy">
>    <rdfs:subPropertyOf rdf:resource="&rdfs;seeAlso"/>
>    <rdfs:domain rdf:resource="&rdf;Resource"/>
>    <rdfs:range rdf:resource="&rdf;Resource"/>
>    <rdfs:comment>
>        This property indicates a resource which fully or partially
>        defines the subject resource.

I insist that we do not put this into a spec unless we also say 
something about what we mean by 'define'. That word has no formal 
meaning in an assertional language like RDF and RDFS, and it is a 
very dangerous word to use casually. (For example, the difference 
between a simple contradiction and a very nasty paradox turns on the 
distinction between 'assert' and 'define', and this has been a 
central issue in the Webont layering problems.). I would prefer to 
avoid the use of the 'define' word altogether if we possibly can, 
particularly when used with 'resource'.

>The subject of this property
>        can be any instance of rdfs:Resource and may have as its
>        value any rdfs:Resource.

Why bother saying that? *Everything* is an instance of rdfs:Resource, 
so this isn't saying anything.

>The most common anticipated usage
>        is to relate a vocabulary term to an instance of rdfs:Schema
>        containing defining information about that term.
>    </rdfs:comment>
><rdfs:Class rdf:about="&rdfs;Schema">
>    <rdfs:comment>
>       An RDF/XML instance.
>    </rdfs:comment>
>(and no, I don't consider the definition of rdfs:Schema to be
>  too narrow; folks can still point to N3 instances if they like,
>  but an rdfs:Schema is a standard serialization of RDF statements)
>Patrick Stickler              Phone: +358 50 483 9453
>Senior Research Scientist     Fax:   +358 7180 35409
>Nokia Research Center         Email: patrick.stickler@nokia.com

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Received on Wednesday, 12 June 2002 13:35:39 UTC

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