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Re: Limitations of OWL 1.1 to RDF mapping

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 17 Nov 2006 15:36:58 -0600
Message-Id: <p06230907c183dab21421@[10.100.0.128]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
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.

I was referring to the claim in the last sentence 
of the above, which refers to first-order logic 
and uses the word "impossibility", and refers to 
the RDF style of SEMANTICS (my emphasis). That 
sentence is rather hard to parse, however (what 
exactly is the phrase "along this line" intended 
to refer to? I assumed, after some thought, that 
it refers to the "line" of NOT using punning, 
rather than the "line" adopted in OWL 1.1) and I 
may have misunderstood it: if so, I apologize.

BTW, I am not defending the idea that 'all syntax 
is triples'; but that point is moot, since the 
entire thread is predicated on the assumption 
that at least the SYNTAX will indeed be triples.

Pat

>Peter F. Patel-Schneider
>Bell Labs Research


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Received on Friday, 17 November 2006 21:37:31 GMT

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