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Re: I have a trouble with The RDF Model

From: pat hayes <phayes@ai.uwf.edu>
Date: Mon, 4 Dec 2000 16:23:11 -0600
Message-Id: <v0421010db651c81d6749@[205.160.76.86]>
To: guha@guha.com
Cc: www-rdf-logic@w3.org
>I think this confusion between the graph being the semantic
>thing vs being a higher level syntax is an artifact of the
>extremely limited expressiveness of RDF today.
>
>Without connectives or quantifiers (and no, reification
>does give us a way out of this),

does or does not?

> there is a certain
>isomorphism between the triple syntax and the semantic model
>(the graph) which is very confusing.

Well, yes and no. The structures are isomorphic, but the relationship 
between the expressions of the language and their interpretations are 
usually fundamentally different from those between abstract and 
concrete syntax. For example, typically the more things one says, the 
more one *constrains* the set of possible interpretations, so that 
the set of interpretations which satisfy the assertions gets smaller 
as the set of assertions increases; exactly the opposite for the 
syntactic relationships.  (Which is what makes me suspicious of your 
answer that the graphis best regarded as an interpretation of the 
RDF.)

>At some point, when we bite the bullet and introduce
>connectives and variables as language constructs into
>RDF, I think the difference between the syntax and
>semantics will become clearer.

Well, I surely hope so. RDFS for example seems to want to be about 
things like classes and properties, rather than about graphs.

Pat

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Received on Monday, 4 December 2000 17:21:40 GMT

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