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Re: Refactoring OWL Lite - a proposal based on implementation in rule-based systems

From: Dan Connolly <connolly@w3.org>
Date: 04 Oct 2002 15:17:02 -0500
To: Raphael Volz <volz@aifb.uni-karlsruhe.de>
Cc: Webont <www-webont-wg@w3.org>, ls3 <ls3@aifb.uni-karlsruhe.de>
Message-Id: <1033762622.14910.2101.camel@dirk>

On Fri, 2002-10-04 at 12:21, Raphael Volz wrote:
> The proposal is motivated by Datalog theory, and 
> can be easily implemented on top of cheap, existing, off-the-shelve and 
> widely availabe technology.

Why do you separate the statements in an ontology from other
sorts of statements?

In section 4 Representation of RDF in rule-based systems, I
see the straightforward prolog representation of RDF triples...

  OWL ontologies are syntactically represented in RDF. This would
  allow a very simple form of representation,which maps each
  RDF statement to one logical ternary predicate
  statement(subject, predicate, object).

(statement is called 'rdf' in our recent work with otter,
and it's called PropertyValue in the DAML+OIL KIF axioms)

But then why do you use the rule schema...

  D(X) : - C(X).

for subClassOf, rather than the straightforward representation
	statement(D, rdfs:subClassOf, C).
along with one generalized rule...
	statement(X, rdf:type, D) :- statement(D, rdfs:subClassOf, C),
		statement(X, rdf:type, C).

That would get around some of the problems with enumerations; e.g.
we can get from
	:MyBrothers owl:oneOf (:Bob :John).
	:Bob rdf:type :MyBrothers

with a rule:

	statement(X, rdf:type, C) :- statement(C, owl:oneOf, L),
		statement(X, owl:member, L).

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Friday, 4 October 2002 16:16:42 UTC

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