- From: Peter Crowther <Peter.Crowther@networkinference.com>
- Date: Wed, 5 Mar 2003 08:36:30 -0000
- To: "Bob MacGregor" <macgregor@ISI.EDU>, "Dan Connolly" <connolly@w3.org>
- Cc: <www-rdf-logic@w3.org>
> From: Bob MacGregor [mailto:macgregor@ISI.EDU]
> GreaterThan is a transitive Datatype Property.
> Equals is a symmetric Datatype Property.
While that's true, those aren't fully built into OWL - there's an
implicit notion for cardinality constraints, but nothing more to my
knowledge.
I see that you may want to make these explicit for some queries. We do
this in Cerebra, but we have (deliberately) done so by exposing XML
Schema restrictions and facets within our datatypes so that you can
specify {min,max}{Inclusive,Exclusive} rather than by doing it through
the logic itself. Doing it this way allowed us to avoid the nasty
questions about what happens if you combine a built-in ordering (say
GreaterThan on integers) with user-defined datatype axioms (for example,
asserting 0 GreatherThan 1000). Amongst the other benefits, this gave
us a very fast datatype reasoner for the standard integer and float
types --- it's always good to have hardware support for your operations
;-).
Bob, would you see this as being useful for assertions, for queries, or
both? And would your answer change any if XML Schema restrictions and
facets were available?
- Peter
Received on Wednesday, 5 March 2003 03:36:39 UTC