- From: Bijan Parsia <bparsia@isr.umd.edu>
- Date: Mon, 12 Dec 2005 19:57:54 -0500
- To: Michael Kifer <kifer@cs.sunysb.edu>
- Cc: "Evan K. Wallace" <ewallace@cme.nist.gov>, public-rif-wg@w3.org
On Dec 12, 2005, at 7:29 PM, Michael Kifer wrote: [snip] > There was a discussion of whether the query language (SPARQL) has > negation > and Bijan said that the existentials get us there. > This is something that I don't understand. *Universal quantification* > in a > query language introduces negation. But existential conjunctive queries > without explicit negation are Horn clauses and are within Datalog. > For those queries the classical equivalence of logical implication, > least > fixpoint, and the unique min model holds. > > Bijan, please elaborate. I'm trying to reconstruct what I was thinking... Hmm. I think it was a brain fart. That or I was conflating the difficulties you get with RDF and OWL kbs. Hmm. I think I was thinking of counting, not negation, and how generated individuals muck with that. But it came out seriously garbled. But, be that as it may, clearly the text in the minutes is a boo boo (and definitely not the scribes fault). Cheers, Bijan.
Received on Tuesday, 13 December 2005 00:58:16 UTC