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

Re: refining closure text for rdfs-isDefinedBy-semantics

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Thu, 13 Jun 2002 11:20:05 +0300
To: Pat Hayes <phayes@ai.uwf.edu>
CC: RDF Core <w3c-rdfcore-wg@w3.org>
Message-ID: <B92E3065.16A9A%patrick.stickler@nokia.com>

On 2002-06-12 20:35, "ext patrick hayes" <phayes@ai.uwf.edu> 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'.

Would you like to suggest a word to use other than 'define' that
fits into the above text?

>> 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.

It certainly is. It's saying that it is not simply an RDF/XML instance
or some other schema. It's being very explicit that it *can* be
anything, even if frequent practice favors one particular type of
resource.

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 04:15:54 EDT

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