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Re: Limitations of OWL 1.1 to RDF mapping

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 17 Nov 2006 15:47:58 -0500 (EST)
Message-Id: <20061117.154758.71122960.pfps@research.bell-labs.com>
To: phayes@ihmc.us
Cc: der@hplb.hpl.hp.com, bparsia@isr.umd.edu, public-owl-dev@w3.org

From: "Pat Hayes" <phayes@ihmc.us>
Subject: Re: Limitations of OWL 1.1 to RDF mapping
Date: Fri, 17 Nov 2006 13:31:09 -0600

[...]

> BTW, the statement later in the paper,
> 
> "The possibility of continuing along this line [that is, the RDF 
> style of semantics] in OWL 1.1 is called even more into question by 
> the impossibility of extending it to Semantic Web languages with 
> expressive power on a par with that of First-Order Logic"
> 
> is also false, or at best highly misleading. The ISO Common Logic 
> draft standard (http://cl.tamu.edu/#cl) uses the same basic semantic 
> construction as that used in RDF, i.e. unrestricted use of names, 
> without punning, in a full first-order framework, in exact harmony 
> with the semantics of RDF. Although ISO CL is unusually liberal in 
> its syntax, the actual logic (without sequence markers) is 
> first-order logic by all accepted semantic criteria (for example, it 
> satisfies compactness and Skolem-Lowenheim), and can be processed 
> using conventional first-order inference engines. This work has been 
> publicly available for open comment now for over three years, and has 
> been commented on by at least some of the authors of this paper. A 
> more recent extension called IKL 
> (http://www.ihmc.us/users/phayes/IKL/GUIDE/GUIDE.html ) continues 
> (and utilizes) this semantic construction to extend the expressivity 
> considerably beyond first-order logic, and is apparently known to at 
> least some of the authors, as they have asked me about it personally. 
> I can therefore only surmise that the reiteration of this falsehood 
> in a recent publication is a deliberate attempt to mislead readers, 
> in what appears to be a continuing and systematic attempt to diss 
> RDF. I am at a loss to understand the motivation for this apparently 
> self-destructive behavior.
> 
> Pat Hayes

The above quote has the following context:

    A triple syntax is being provided for OWL 1.1, syntactically compatible
    with the triple syntax for OWL DL. However, for the above reasons, this
    syntax could not be given a meaning compatible with the RDF meaning for
    triples, at least not without some very difficult semantic tiptoeing
    (as well as some questionable encoding (such as creating fresh URI
    references for punning purposes, e.g., using Person-the-Class and
    Person-the-Individual instead of just Person). The appropriateness of
    continuing along this line with OWL 1.1 is called even more into
    question by the impossibility of extending it to Semantic Web languages
    with expressive power on a par with that of First-Order Logic [15].
    
    [Next Steps for OWL, Bernardo Cuenca Grau, Ian Horrocks, Bijan Parsia,
    Peter Patel-Schneider and Ulrike Sattler, 2006 OWL Experiences and
    Directions workshop, Athens, Georgia, 10-11 November 2006, p. 6,
    currently available at
    owl-workshop.man.ac.uk/acceptedLong/submission_11.pdf]

This context indicates that the impossibility involves maintaining key
aspects of RDF, including 1/ all syntax is triples and 2/ all triples have
at least their basic RDF meaning as facts.  As the ISO Common Logic draft
standard does not have these aspects it can hardly be used as a
counterexample to the claim.

Peter F. Patel-Schneider
Bell Labs Research
Received on Friday, 17 November 2006 20:48:14 GMT

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