- From: Jos de Bruijn <debruijn@inf.unibz.it>
- Date: Tue, 31 Mar 2009 18:36:02 +0200
- To: RIF WG <public-rif-wg@w3.org>

In the discussion in our meeting just now, besides the options I mentioned: > So, either (a) we say that you effectively leave Core when going for OWL > 2 RL or (b) we provide an embedding of an equality-free subset. > I would be in favor of (a), because I do not want to define yet another > OWL subset; I think the whole web of semantic Web languages is already > complicated enough. support was expressed for option (c) provide a general embedding in BLD, but specify a subset of RIF-OWL combinations for which you stay in RIF Core and for option (d) add an embedding of equality; this embedding will depend on the predicate symbols used in the ruleset at hand. Jos Jos de Bruijn wrote: > It is impossible to completely coreify the embedding of OWL 2 RL > combinations, because there is equality in that language. A naïve > axiomatization such as use of sameAs (as in [1]) is not sufficient, > because in combinations one can use arbitrary predicates. > > For example, if the ontology says: > FunctionalProperty(p) > ClassAssertion(C a) > PropertyAssertion(p e a) > PropertyAssertion(p e b) > > With the naïve sameAs axiomatization we can derive > a[sameAs -> b] and b[rdf:type -> C] > > However, if we add the RIF fact > q(a) > > we cannot derive q(b) unless we have a full-blown axiomatization of > equality (which is doable because there are no function symbols in > Core). This would, however, clearly defeat the purpose of not having > equality in Core. > > So, either (a) we say that you effectively leave Core when going for OWL > 2 RL or (b) we provide an embedding of an equality-free subset. > I would be in favor of (a), because I do not want to define yet another > OWL subset; I think the whole web of semantic Web languages is already > complicated enough. > > > Best, Jos > -- +43 1 58801 18470 debruijn@inf.unibz.it Jos de Bruijn, http://www.debruijn.net/ ---------------------------------------------- Many would be cowards if they had courage enough. - Thomas Fuller

Received on Tuesday, 31 March 2009 16:36:53 UTC