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SEM: Reaching consensus (was Re: third version of semantics document)

From: Jim Hendler <hendler@cs.umd.edu>
Date: Thu, 29 Aug 2002 08:51:40 -0400
Message-Id: <p05111703b993c6608660@[]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: phayes@ai.uwf.edu, www-webont-wg@w3.org

At 6:48 AM -0400 8/29/02, Peter F. Patel-Schneider wrote:
>From: Jim Hendler <hendler@cs.umd.edu>
>Subject: Re: third version of semantics document
>Date: Wed, 28 Aug 2002 17:38:05 -0400
>>  At 10:48 AM -0400 8/28/02, Peter F. Patel-Schneider wrote:
>>  >As an indication of how things can go wrong in a complicated specification,
>>  >Pat's document is very close to implying that all RDFS classes and
>>  >properties are OWL objects.
>>  [snip]
>>  >
>>  >peter
>>  Peter, for those of us who are not as logically inclined as you,
>>  could you make it clear why the above would be a problem and what the
>>  consequences would be? If someone asked me "Should RDFS classes and
>>  properties be OWL objects" I would have assumed the answer should be
>>  yes
>>    thanks
>>    JH
>The first paragraph of section 1 of the document states that individuals
>are not classes or properties.  QED

I didn't ask you to prove it, I asked you to help some of us 
understand what it means in practice and what the implications would 

The reason for this is simple, and I think ALL of you logic oriented 
folks need to think about it a bit:

  The consensus approach means that many of us in the WG who do not 
read model theories by training or parse XML in our sleep must also 
be convinced the solution is a good one.  Currently the abstention 
camp outweighs those voting, and it is this group that will actually 
be crucial to making the decision.

As I have often in the past, I quote our charter:

>  The  Working Group shall start by evaluating the technical 
>solutions proposed in the DAML+OIL draft. If in this process the 
>Working Group finds solutions that are agreed to be improvements 
>over solutions suggested by DAML+OIL, those improved solutions 
>should be used.

note the word AGREED - if we don't have consensus on this issue, with 
more than a small group of logicians stating it is solved, we are not 
done -- the rest of the WG will need to be convinced.

Further, I point out the following from our charter

>1.2.2 Formal Semantics
>Moreso than for a traditional programming language, a knowledge 
>representation language needs a formal semantics to clearly 
>delineate what is, and is not, entailed from any particular language 
>construct or combination thereof. Such a formal semantics may be in 
>a denotational or axiomatic form. Examples of both of these have 
>been produced for DAML+OIL, providing examples of what is necessary 
>for the WebONT language products.

Note that this does not mandate us to do a denotational (model 
theoretic) semantics) - and we've been told be several people in the 
current debate that an axiomatic (and I think Lbase would count) 
approach would be easier.

I think we all agree we would like a formal semantics including a 
model theory.  I am willing to believe that good progress is being 
made, and that we have at least a chance of reaching a consensus. 
However, if the bulk of the WG is not convinced, the charter allows 
us a lot of leeway to simply point at the weak D+O  MT and write some 
stuff about the changes our successor group might want to consider 
(i.e. resolve some of the semantic issues as POSTPONED).  So helping 
the rest of us in the WG understand the ramifications of your 
approaches IS important.

I know that I have more logical training and AI background than some 
people in this WG, but the current conversation is reaching a point 
of obtruseness that I simply cannot follow - which implies the same 
is true of some other WG members.  I am therefore reminding ALL sides 
of the semantic camp that helping the rest of understand the issues 
is part of what you need to do.

  Jim H.

Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742	  240-731-3822 (Cell)
Received on Thursday, 29 August 2002 08:51:50 UTC

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