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Re: summary of current position with respect to semantics proposals (was Re: WOWG: agenda Aug 15 telecon)

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 14 Aug 2002 23:44:35 -0400
To: connolly@w3.org
Cc: www-webont-wg@w3.org
Message-Id: <20020814234435F.pfps@research.bell-labs.com>

From: Dan Connolly <connolly@w3.org>
Subject: Re: summary of current position with respect to semantics proposals 		(was Re: WOWG: agenda Aug 15 telecon)
Date: 14 Aug 2002 14:29:29 -0500

> On Wed, 2002-08-14 at 13:17, Peter F. Patel-Schneider wrote:

[...]

> > Extending the approaches in the two proposals to the logic layer would
> > result in Proposal [1] supporting and Proposal [2] not supporting
> > 
> > Entailment 2:
> > 	`it is raining'  or  `today is Tuesday'
> > 	entails
> > 	`today is Tuesday'  or  `it is raining'
> 
> I think this discussion of extension to the logic layer is
> something of a red herring, but in fact, that entailment
> *does* follow if you look at log:or as a property that
> relates two (quoted) formulas. It can be axiomatized
> without resorting to existentials in the conclusion of any rules,
> so it works fine:
> 
> From
>   { :it :is :raining } log:or { :today :is :Tuesday }.
>   log:or a ont:SymmetricProperty.
> along with the usual rules for SymmetricProperty, we deduce
>     { :today     :is :Tuesday . } log:or {:it  :is :raining .} .
> 
> 
> In more traditional first-order logic syntax, that would
> look more like:
> 
> 	(PropertyValue log:or '(is it raining) '(is today Tuesday))
>         (PropertyValue rdf:type log:or ont:SymmetricProperty)
> 
> ==>
> 
> 	(PropertyValue log:or '(is today Tuesday) '(is it raining))
> 
> and yes, quantifying into quoted formulas is messy.
> 
> I don't claim that this log:or design is the way to go;
> new syntax is necessary for universal quantification,
> and quite likely cost-effective for negation and
> maybe even disjunction.

log:or, as described above, has nothing to do with logical disjunction.  So
of course it is quite easy to make it symmetric but that doesn't speak to
the argument above at all.

[...]

peter
Received on Wednesday, 14 August 2002 23:44:43 GMT

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