Re: A Problem With The Semantics of DAML+OIL Restrictions

Concerning the issue of cardinality of toClass and hasValue etc...
I comment inline below:

Richard Fikes wrote:

> Thanks for your reply to my message.  I know you followed up your first
> reply with a second one saying that perhaps the problem was not as
> easily dealt with as you had suggested in your first reply.  However, I
> think it may be useful to comment on some of the points in your first
> reply.
>
> > Hmm... I consider onProperty and toClass to be
> > UniqueProperties, i.e. cardinality 1.
> >
> > I thought that was in the axiomatic or model-theoretic
> > semantics somewhere; if not, I'd consider that a bug.
> > And of course it should be in the prose etc.
>
> I don't see anything in the language spec documents that restrict
> toClass, hasValue, etc. to be unique properties.  If that is the
> intention of the language design committee, it would be useful for the
> committee to say that and of course to add that to the spec documents.

I think there was never any intention for hasValue to have cardinality1  in
fact, just the opposite, I think it may be typical to have multiple values.

I also did not think that the toClass had a uniqueness assumption.

what happens if one generates a restriction on say hasFriend  to the class
AmericanCitizen and then later add a restriction on hasChild again to be say
WineLover.

This would result in two toClass values.
 I am not sure that given that we let people add other things incrementally that
it makes sense not to allow them to add restrictions on the same property
incrementally.

--
 Deborah L. McGuinness
 Knowledge Systems Laboratory
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Received on Monday, 2 July 2001 19:32:23 UTC