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Re: model theory for RDF/S

From: Pat Hayes <phayes@ai.uwf.edu>
Date: Wed, 26 Sep 2001 17:23:45 -0500
Message-Id: <p05101032b7d803c50c02@[]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-logic@w3.org
>One more problem with the model theory.
>Even if all aspects of reification and containers are removed from RDF>
>There is still the matter of rdf:type
>In ``5. Formal Model for RDF'' of M&S, there are the requirements that
>  5. There is an element of <I>Properties</I> known as RDF:type.
>  6. Members of <I>Statements</I> of the form {RDF:type, sub, obj} must
>     satisfy the following: sub and obj are members of <I>Resources.</I>
>     [...]
>These conditions are not captured in the model theory.

Well, they are in a sense.  I am not sure how to interpret 5 as a 
requirement on RDF, other than as a syntactic requirement on the 
vocabulary, in which role it has no bearing on the model theory of 

Like the rest of the M&S, condition 6 is careless about use and 
mention; I assume it was intended to say that the subject and object 
*denote* members of the set of Resources. (This is a semantic 
requirement in the metatheory, not an assertion in RDFS, since it 
uses the form:  <I>Resources.</I> rather than: 
<code>rdfs:Resource</code>, right?)  With this understanding, it 
seems to follow automatically, since IR is required to consist of 
resources by the model theory.  On the other hand, if it intended to 
be interpreted strictly literally, then it seems to be an assertion 
about the semantic status of pieces of RDF syntax, which would have 
no model-theoretic consequences at all in the absence of reification.


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Received on Wednesday, 26 September 2001 18:23:38 UTC

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