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Re: Declarative limitations of OWL/DAML

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Tue, 25 Mar 2003 12:52:45 +0000
Message-ID: <16000.20765.586795.767202@merlin.horrocks.net>
To: Dave Reynolds <der@hplb.hpl.hp.com>
Cc: lchewhun@dso.org.sg, www-rdf-logic@w3.org

On March 25, Dave Reynolds writes:
> lchewhun@dso.org.sg wrote:
> > 
> > I'm interested in what CANNOT be represented (declared) in OWL/DAML. Your
> > comments or pointers to papers are much appreciated.
> > 
> > What I'm hoping to do is to be able to represent constraints (or axioms or
> > rules) in a DAML ontology so that an inferencing engine can check the ontology
> > for consistency.  
> Ian Horrocks and Benjamin Grosof have some working papers such as [1] which
> compare expressivity of DAML/OWL to rule or logic programming languages. In
> particular, they point out that DL languages can't represent predicates
> involving multiple variables or involving predicate chains other than transitive
> closures. Thus a constraint such as "my grandfather must be older than me" would
> be tricky on both counts.

A couple of points. DLs certainly CAN represent predicates involving
multiple variables and predicate chains, it just happens that the
particular DL on which DAML/OWL are based does not include these
features (there are a variety of reasons for this, not the least of
which is the fact that the RDF and XML type systems do not specify
n-ary predicates). See [2,3] for details about DL support for datatypes
(called concrete domains in DLs).

I would also suggest looking at [4] (a recent paper) if you are
interested in the work Benjamin and I (along with Raphael Volz and
Stefan Decker) have done on integrating DAML/OWL with rule or logic
programming languages.

Regards, Ian

[2] http://lat.inf.tu-dresden.de/~clu/papers/archive/aiml4.ps.gz
[3] http://lat.inf.tu-dresden.de/~clu/papers/archive/lutzdiss.pdf
[4] http://www.cs.man.ac.uk/~horrocks/Publications/download/2003/p117-grosof.pdf

> Personally I think the semantic web will need a rich constraint expression
> language eventually, perhaps it could build upon something like OCL by using
> path expressions to identifying the values being constrained?
> Dave
> [1] http://www.cs.man.ac.uk/~horrocks/Private/DLP/DLP-v9-brief.pdf
> -- 
> Hewlett-Packard Laboratories    | Phone: +44-117-3128165
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> Bristol BS34 8QZ, UK            | dave.reynolds@hpl.hp.com
Received on Tuesday, 25 March 2003 06:52:10 UTC

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