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Re: Possible semantic bugs concerning domain and range

From: Jos De_Roo <jos.deroo.jd@belgium.agfa.com>
Date: Tue, 15 Oct 2002 23:47:39 +0200
To: "Dan Connolly <connolly" <connolly@w3.org>
Cc: Ian Horrocks <horrocks@cs.man.ac.uk>, Pat Hayes <phayes@ai.uwf.edu>, www-webont-wg@w3.org, www-webont-wg-request@w3.org
Message-ID: <OF38B4A715.8B15A1E0-ONC1256C53.00779BDF-C1256C53.0077B9BF@agfa.be>


>> >>  Range(P, A) -> (forall x,y P(x,y) -> A(y) )
>> >>
>> >>  You want
>> >>
>> >>  Range(P,A) <-> (forall x,y P(x,y) -> A(y) )
>> >>
>> >>  They are about equally clear and intuitive; but the latter rules out
>> >>  some possibilities which the former permits. I believe that all the
>> >>  'intuitive' entailments that people want in fact hold in both these
>> >>  cases; and that the former is therefore to be preferred.
>> >
>> >I am agnostic about which of these is to be preferred - as a humble
>> >engineer, all I need to know is which one it is so that I have a clear
>> >spec to which I can build my systems.
>
>I'm kinda agnostic too... I was leaning toward the IF, rather
>than the IFF...

I'm not agnostic at all...
i.e. I can't see how to write
  (forall x,y P(x,y) -> A(y)) -> Range(P,A)
in Horn-clauses or in Datalog
(although I like nested implications
in propositional proof arguments)

[...]

-- ,
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Tuesday, 15 October 2002 17:48:19 GMT

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