- From: Enrico Franconi <franconi@inf.unibz.it>
- Date: Wed, 18 Jan 2006 15:27:18 +0100
- To: Bijan Parsia <bparsia@isr.umd.edu>
- Cc: Dan Connolly <connolly@w3.org>, Pat Hayes <phayes@ihmc.us>, RDF Data Access Working Group <public-rdf-dawg@w3.org>
On 18 Jan 2006, at 15:11, Bijan Parsia wrote: > > On Jan 18, 2006, at 5:55 AM, Enrico Franconi wrote: > >> On 18 Jan 2006, at 04:58, Pat Hayes wrote: > [snip] >>> I am still bothered by the possibilities of OWL-specific notions >>> of redundancy in answer sets. Consider an OWL/RDF KB that asserts >>> >>> :a rdf:type :A >>> :a rdf:type :B >>> :a rdf:type :C >>> :A rdf:type owl:Class >>> :B rdf:type owl:Class >>> :C rdf:type owl:Class >>> >>> and an OWL query >>> >>> SELECT ?x WHERE {:a rdf:type ?x .} > [snip] >>> Now, this dataset OWL-entails the *existence* of a triple >>> intersection and three double intersections, all with :a in them. >>> So are these reasonable answer bindings for such a query? I see >>> no good reason why they should not be: > [snip] > > How about all the disjunctions involving them? (Or all disjunctions > rooted in them?) Or all min 0 restricitons? > > It's very very very tricky. I've been thinking about such queries > and the obvious (first step) restrictions to the binding of ?x are > URIs and explicit/told bnodes (for cases where someone has made an > type assertion to an anonymous class). I tend to think that fishing > expeditions of this sort are just going to die hard. I agree. > (Syntactically there's a fairly sever problem, IMHO, in that you > can't current return an expression as a binding. So you'd have to > rely on bnode stability in more contexts.) > > Retrieving the named types + forcing the user to speculate about > complex expressions, or maybe adding asserted complex expressions > seems to be at the limit of what we know how to do reasonably well > (from an interface standpoint) and the former is all I've seen > implemented or proposed. I agree. And if UMD agrees, since they are OWL-full experts and supporters, then we are in safe hands. cheers --e.
Received on Wednesday, 18 January 2006 14:27:35 UTC