- 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
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 UTC