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Re: refining closure text for rdfs-isDefinedBy-semantics

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Thu, 13 Jun 2002 11:24:09 +0300
To: ext Dan Brickley <danbri@w3.org>, Frank Manola <fmanola@mitre.org>
CC: Pat Hayes <phayes@ai.uwf.edu>, RDF Core <w3c-rdfcore-wg@w3.org>
Message-ID: <B92E3159.16AA1%patrick.stickler@nokia.com>

On 2002-06-12 23:32, "ext Dan Brickley" <danbri@w3.org> wrote:

> 
> 
> Which is one of several reasons I wish it were just called rdfs:namespace :(

Perhaps, since the central motivation for this property is to
associate a term with a schema, and we already have rdfs:seeAlso,
maybe we could just remove/deprecate rdfs:isDefinedBy and
create a new property rdfs:schema which takes rdfs:Schema as
its range?

Also, since a given functional vocabulary can employ multiple namespace
prefixes for its terms, and there is no formal, explicit notion
of an XML Namespace in the RDF graph, I suggest we avoid the use
of the term 'namespace' entirely.

Cheers,

Patrick

> dan
> 
> On Wed, 12 Jun 2002, Frank Manola wrote:
> 
>> 
>> Pat--
>> 
>> How about some suggestions for what we ought to mean by "define"?
>> Especially since it's hard to avoid the use of "define" when trying to
>> describe "isDefinedBy".
>> 
>> --Frank
>> 
>> patrick hayes wrote:
>>> 
>>>> On 2002-06-11 10:29, "ext Patrick Stickler" <patrick.stickler@nokia.com>
>>>> wrote:
>>>> 
>>>>> 
>>>>>  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:Property>
>>>> 
>>>> <rdfs:Class rdf:about="&rdfs;Schema">
>>>>    <rdfs:comment>
>>>>       An RDF/XML instance.
>>>>    </rdfs:comment>
>>>> </rdf:Class>
>>>> 
>>>> (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)
>>>> 
>>>> Cheers,
>>>> 
>>>> Patrick
>>>> 
>> 
>> 
>> 
> 
> 

--
               
Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Thursday, 13 June 2002 04:20:10 EDT

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