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Meta-classes? (layered architecture)

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Mon, 16 Oct 2000 13:46:36 +0100 (BST)
To: www-rdf-logic@w3.org
Message-ID: <14826.61699.999113.87444@localhost.localdomain>
We need to be clear as to whether or not it is intended that DAML-ONT
classes (relations) denote classes of objects (binary relations
between objects) or whether they could also denote classes of classes,
classes of relations etc. (it doesn't matter what we consider an
"object" to be - it is simply something that our ontology language
treats as an atom).

In OIL, it was explicitly decided that, in the base language, the
denotation of classes and relations should be sets of objects and
binary relations between objects, and that meta-extensions, if
required, would be provided in additional language layers (yet to be
defined). The rationale behind this layered architecture is that we
should extend RDFS in relatively small increments (in the same way
that RDFS is a small increment w.r.t. RDF). This makes it more likely
that widespread agreement can be reached on the specification of any
given increment, allows for extension along multiple axes, and gives
applications designers a choice about the language layer that they
want to commit to, rather than the "all or nothing" choice that is
presented by a single large language.

It has been suggested that DAML languages will also have a layered
architecture, and that further layers (DAML-RULES, DAML-LOGIC) will
follow. If this is the case then I think it makes sense to stick to
the simple thing for now and leave meta-classes for DAML-META.

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 09:07:47 UTC

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