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Re: RDFCore WG 2001-06-01 Teleconference Agenda

From: Graham Klyne <Graham.Klyne@Baltimore.com>
Date: Wed, 06 Jun 2001 12:49:21 +0100
Message-Id: <5.0.2.1.2.20010606123821.0373cec0@joy.songbird.com>
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: rdf core <w3c-rdfcore-wg@w3.org>
At 09:48 AM 6/7/01 +0100, Brian McBride wrote:
>Graham Klyne wrote:
>[...]
> > More recent discussion on the RDF-logic list has focused on the
> > relationship between "reification" and syntax, and the nature of RDF
> > "syntax".  A viewpoint that emerges from this discussion is that the RDF
> > structure of triples is too simple to attach any meaningful
> > semantics;
>
>Graham, do you really mean 'any meaningful semantics', or do you mean
>that it is not syntactically rich enough to support, for example expressions
>with quantifiers.  It seem to me rich enough to support the assertion of
>'ground facts' with the semantics defined in the definition of the
>semantics of the URI's involved.

(That was an unfortunate turn of phrase I used ;-)

But, yes, for example, the syntax (defined simply in terms of triples) is 
not rich enough to support expressions with quantifiers.  One can use the 
triples to encode some richer syntax (e.g. as one uses character sequences 
to encode programming language constructs) that is capable of supporting 
this, but that would be a different syntax hence a different language.

So, to define a useful level of semantics, there must be a sufficiently 
rich syntactic structure.

The DAML+OIL model theoretic semantics does this by associating semantics 
with combinations of triples with certain values in certain places -- a 
structure that is not captured in the basic syntax (construction rules) for 
RDF.

Another approach would be to re-cast the abstract syntax of RDF in a richer 
syntax that recognizes the particular forms to which which special 
semantics are attached.

For example, the combination of four statements that comprise a reification 
is a syntactic structure  distinct from some arbitrary collection of 4 RDF 
statements.

So when you say:
>   It seem to me rich enough to support the assertion of
>'ground facts' with the semantics defined in the definition of the
>semantics of the URI's involved.

I think you are suggesting a new language whose symbols are RDF ground 
facts:  additional semantics might be associated with certain syntactic 
combinations of such facts (as in the reification example).

#g



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Graham Klyne                    Baltimore Technologies
Strategic Research              Content Security Group
<Graham.Klyne@Baltimore.com>    <http://www.mimesweeper.com>
                                 <http://www.baltimore.com>
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Received on Wednesday, 6 June 2001 07:56:31 EDT

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