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Re: What do the ontologists want

From: Dan Brickley <danbri@w3.org>
Date: Wed, 16 May 2001 07:39:34 -0400 (EDT)
To: pat hayes <phayes@ai.uwf.edu>
cc: Jonathan Borden <jborden@mediaone.net>, <www-rdf-logic@w3.org>
Message-ID: <Pine.LNX.4.30.0105160704010.12499-100000@tux.w3.org>

Hi Pat,

On Tue, 15 May 2001, pat hayes wrote:

> >pat hayes wrote:

[...]
> So it has no semantics at all? I doubt if that is really what you
> mean, since then it would have no point to it, as far as I can see.
> Certainly the RDF literature seems to *want* RDF to actually mean
> something.

I consider RDF content to be meaningful largely by proxy: RDF
piggybacks on URIs, which are meaningful by virtue of
a quasi-mystical social/legal process involving the devolution of naming
rights (via various URI schemes) to individuals and organisations. I'm not
sure how this aspect of meaning (ie. theories of reference) fits with the
DAML+OIL formalisms (the Model-Theoretic and the Axiomatic semantics). The
DAML+OIL documents provide (very useful) rules for inferring
DAML+OIL expressions from other DAML+OIL expressions, but are rather
quiet on the grounding of those structures in social / legal reality.

http://www.daml.org/2001/03/model-theoretic-semantics.html says "This
document ignores all aspects of naming" while appealing to a notion of
DAML+OIL semantic structures being _true_ ("A semantic structure
<AD,IC,IO,IR> is a model for the DAML+OIL ontology if the constraints
 resulting from the mappings from the ontology are true in the
structure."). I find it difficult to understand how the truth
condidtions for DAML+OIL expressions can in practice be usefully reasoned
about by Web applications unless DAML+OIL acquires a theory of reference
/ naming. Without some specification that tells us what (if anything) a
DAML+OIL expression *refers to*, DAML+OIL content will be meaningless.
Maybe I'm misreading the specs, but an account of meaning that ignores
naming / reference is missing something. (Maybe KIF has an attempt at
this? I should probably re-read the KIF docs...)

I'm not complaining about DAML, and I'm not claiming that RFC 2396 (the
URI syntax spec) embodies an adequate theory of reference. Just that we're
in the same boat, in that there's an aspect to meaning (ie. reference)
that all these specs have a problem with.

danbri

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Received on Wednesday, 16 May 2001 07:39:41 UTC

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