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Re: problem introduced by recent change to RDF MT

From: pat hayes <phayes@ihmc.us>
Date: Thu, 12 Jun 2003 10:55:53 -0500
Message-Id: <p05210615bb0e4e307981@[]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-comments@w3.org

>From: pat hayes <phayes@ihmc.us>
>Subject: Re: problem introduced by recent change to RDF MT
>Date: Wed, 11 Jun 2003 15:50:52 -0500
>>  >The recent changes in the RDF MT (10a June 2003) have resulted in the
>>  >following problem:
>>  >
>>  >An rdf interpretation I is now of an arbitrary vocabulary V. 
>>This means that
>>  >the domain of IS is V.  However, V does not necessarily include the members
>>  >of the RDF vocabulary.
>>  True; this was deliberate.
>>  >  This results in the potential breakdown of the RDF
>>  >semantic conditions.  For example, there might not be a domain element
>>  >corresponding to rdf:type.
>>  There might not, indeed, in a simple interpretation of an RDF graph
>>  which did not use the URIref rdf:type; that was true previously, of
>>  course. However, the RDF semantic conditions require that
>>  IEXT(I(rdf:type)) contain at least infinitely many pairs of the form
>>  <x, I(rdf:XMLLiteral)>, so require that I(rdf:type) be in IP; and the
>>  first semantic condition requires that IP be a subset of IR, in every
>>  rdf-interpretation. So the conditions do not break down for rdf- (or
>>  rdfs-) interpretations.
>I guess I didn't make my point correctly.
>If rdf:type is not in V then I(rdf:type) is not defined so there is no way
>that the semantic conditions can say that I(rdf:type) is in IP.

Ah, I take your point.  I think intuitively of all mappings as 
partial on the entire universe, so automatically extendable to a 
larger domain where required by context, but I understand this is not 
widely regarded as kosher.

I have modified the text to refer to (V union crdfV), where crdfV is 
a 'core' vocabulary containing rdf:type, rdf:Property and 
rdf:XMLLiteral. Similarly the RDFS conditions refer to V union crdfV 
union rdfsV. This seems to cover the necessary ground while keeping 
the closures finite.

>>  Pat
>>  PS. It may not be appropriate to be discussing details of an
>>  editorial draft on rdf-comments while it is in a state of flux.
>Hmm.  Where else is appropriate then?

Off-list? My understanding was that rdf-comments was intended for 
discussion surrounding the 'official' comments process involving the 
last call documents, and surrounded by the elaborate protocols of 
responses, requests for clarification and so on. But since nobody 
else seems to be objecting, lets just carry on as we are doing.


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Received on Thursday, 12 June 2003 11:56:00 UTC

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