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Re: semantics status of RDF(S)

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 02 Apr 2001 08:16:35 -0400
To: fikes@KSL.Stanford.EDU
Cc: www-rdf-logic@w3.org
Message-Id: <20010402081635L.pfps@research.bell-labs.com>

The axiomatization for RDF and RDF(S) is one avenue that could be used to
provide a firm semantic foundation for RDF and RDF(S).  However, this
axiomatization has (as yet) no status with respect to RDF and RDF(S).
Therefore I feel completely justified in critisizing RDF and RDF(S) as
lacking in semantic grounding.

One desirable effect of criticism of RDF and RDF(S) as lacking in semantic
grounding should be the adoption of formal semantics for RDF and RDF(S).
RDF and RDF(S) currently exist without formal semantics.  Further, there is
no indication in any official RDF or RDF(S) documents that the lack of a
formal semantics was considered to be a problem when RDF and RDF(S) were
developed.  I take this to mean that some people are satisfied with the
current state of affairs.  If no one complains about the lack of a formal
semantics then nothing will be done.

It is at least a bit hopeful that there are some issues in the RDF Issue
Tracking document having to do with the lack of a formal semantics for RDF
and RDF(S). 

Peter 




From: Richard Fikes <fikes@KSL.Stanford.EDU>
Subject: Re: semantics status of RDF(S)
Date: Sun, 01 Apr 2001 20:43:11 -0700

> > 1/ There are many places in the RDF and RDFS documents where vitally
> > important statements about the semantics of RDF or RDFS are presented with
> > no formal backup, and in a totally inadequate fashion. 
> > 
> > For example, in Section 2.3.2 of the RDFS Specification 1.0 there are two
> > paragraphs that give conditions on rdfs:subClassOf.  As far as I can tell,
> > this is the only place that attempts to provide a meaning for rdfs:subClassOf.
> > However, these two paragraphs use terms that are not defined in RDF or RDFS
> > (such as set - classes are not sets and thus the subset relationship is not
> > meaningful on classes), are sloppy in their terminology (rfds:subClass
> > vs. sub/superset vs. subclass), and make unenforceable pronouncements
> > (there is nothing in RDF(S) to prevent someone from creating the triple
> > {rdfs:subClassOf, foo, foo}).
> 
> I am puzzled at this criticism of RDF(S).  It is not news that the RDF
> and RDFS specs do not contain an adequate formalization and semantics. 
> However, as you know, as least one formalization of the semantics or RDF
> and RDFS has been produced and is presented in the paper by Deborah
> McGuinness and myself titled "An Axiomatic Semantics for RDF, RDF
> Schema, and DAML+OIL"
> (http://www.ksl.Stanford.EDU/people/dlm/daml-semantics/abstract-axiomatic-semantics.html). 
> There no doubt have been others.  Criticism of existing formalizations
> of RDF and RDFS would seem more appropriate and productive rather than
> simply criticizing the specs.
> 
> Richard
> 
Received on Monday, 2 April 2001 08:18:10 GMT

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