- From: Bijan Parsia <bparsia@cs.man.ac.uk>
- Date: Mon, 5 Mar 2007 09:45:53 +0000
- To: andy.seaborne@hp.com
- Cc: Lee Feigenbaum <feigenbl@us.ibm.com>, RDF Data Access Working Group <public-rdf-dawg@w3.org>
On Mar 5, 2007, at 9:29 AM, Seaborne, Andy wrote: [snip] > The cardinality for extensions of BGP matching isn't prescribed by > the spec - it's just a matter of an extension deciding what is > appropriate for it's extension. > > http://www.w3.org/2001/sw/DataAccess/rq23/rq25.html#sparqlBGPExtend > > which does not include anything on cardinality induced from blank > nodes in BGPs. Hopefully, that should give freedom to extended > matchings such as OWL-DL. Sorry, I didn't mean to suggest that the spec constrained OWL extensions...but if plain SPARQL has an implicit ALL semantics (or an implicit "best effort" semantics) it will be more consistent to follow that. It seems that even in simpler cases than OWL, ALL might not be easiest (for a number of reasons). If number of (extra) answers in the non-distinct case *never* mattered, then best effort would be fine, but I'm under the impression that people feel strongly for stable numbers of answers in the non-distinct case. Having explicit ALL with no modifier == best effort seems to accommodate all these needs at the cost of departing from the standard SQL behavior. If stable number of (non-distinct) answers doesn't matter, but only an upper bound, then several things become easier spec-wise (though I think that is a bit too loose). Cheers, Bijan.
Received on Monday, 5 March 2007 09:46:13 UTC