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: Fri, 14 Jun 2002 10:39:36 -0500
Message-Id: <p05111a06b92fbceed601@[65.217.30.123]>
To: fmanola@mitre.org
Cc: w3c-rdfcore-wg@w3.org

>Pat--
>
>How about some suggestions for what we ought to mean by "define"?

Perhaps I didn't make my rhetorical point clear enough. I don't think 
it has any meaning. What I would like to say about "isDefinedBy" is 
something like "this is completely meaningless, but if it makes you 
feel good, you can use it to point to something."  Which, of course, 
would make one wonder just why we even have "isDefinedBy" in the 
language at all. Yes, exactly.

I'm willing to be disabused. If someone in the WG thinks it does mean 
something, then by all means explain what that is, preferably with a 
test case involving an entailment. But saying, in essence, " 
'isDefinedBy' means is defined by" , doesn't actually tell the reader 
(or me) anything.

Pat


>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
>>  >
>
>
>--
>Frank Manola                   The MITRE Corporation
>202 Burlington Road, MS A345   Bedford, MA 01730-1420
>mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-8752


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Received on Friday, 14 June 2002 11:39:38 EDT

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