Re: Suggested changes to concrete datatypes proposal

From: Ian Horrocks (
Date: 01/30/01


This was basically my first idea, but Uli Sattler pointed out that
there are serious problems with the negation of modal atoms. Let's say
we have x R d, x abstract and d concrete, and x has no other R
successors. x is not in the restriction hasType R C for some abstract
class C, so it is in the negation of that restriction. That means that
it is in the restriction toType R (not C). The semantics of this
restriction say that every R successor is a (not C). The semantics you
want for negation makes (not C) be a subset of the abstract domain,
but we have an R successor d that is in the concrete domain.


On January 30, Peter F. Patel-Schneider writes:
> This problem can be removed by employing the (admittedly counter-intuitive)
> notion of having complement be relative to the abstract sub-domain.
> peter
> From: Ian Horrocks <>
> Subject: Re: Suggested changes to concrete datatypes proposal
> Date: Tue, 30 Jan 2001 18:38:20 +0000 (GMT)
> > Peter,
> > 
> > As you say, preventing 3 from degenerating into 1 is difficult. I
> > think that what you have proposed below suffers from the problem I
> > mentioned in my reply to Jeff. i.e., when you negate modal atoms you
> > get an implicit union of abstract and concrete types. This is the
> > reason for having separate concrete and abstract properties.
> > 
> > Ian

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