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Re: comparing DAML-ONT and OIL (was Re: semantics of daml)

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Mon, 16 Oct 2000 13:48:26 +0100 (BST)
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: connolly@w3.org, phayes@ai.uwf.edu, www-rdf-logic@w3.org
Message-ID: <14826.63134.583370.565525@localhost.localdomain>
On October 15, Peter F. Patel-Schneider writes:
> From: Dan Connolly <connolly@w3.org>
> Subject: Re: comparing DAML-ONT and OIL (was Re: semantics of daml)
> Date: Sat, 14 Oct 2000 22:59:58 -0500
> 
> > "Peter F. Patel-Schneider" wrote:
> > > 
> > > 
> > > Capabilities
> > > 
> > >   Built in Classes              thing, nothing          thing, nothing
> > 
> > I'm not sure what "built in" classes are... in DAML,
> > Thing and Nothing are just classes, like Property
> > and Class and Animal and all the rest.
> 
> Built-in classes have prespecified meanings.  This makes Thing very
> different from Animal.  DAML-ONT inherits more built-in classes from RDF,
> such as Class, but I didn't include them.

Actually, the built in classes "Thing" and "Nothing" are just
conveniences (syntactic sugar) and add nothing to the language. The
construction "a OR NOT a", where a is any class, can be used instead
of Thing, while "a AND NOT a" can be used instead of Nothing. However, 
as Thing (in particular) and Nothing are common idioms, it is usual to 
have this meaning "built-in" to the language.

Ian
--
Ian Horrocks, Department of Computer Science,
University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Tel: +44 161 275 6133  Fax: +44 161 275 6204  Email: horrocks@cs.man.ac.uk
URL: http://www.cs.man.ac.uk/~horrocks
Received on Monday, 16 October 2000 09:11:12 GMT

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