- From: <ewallace@cme.nist.gov>
- Date: Thu, 15 Dec 2005 12:41:03 -0500 (EST)
- To: kifer@cs.sunysb.edu, bparsia@isr.umd.edu
- Cc: ewallace@cme.nist.gov, public-rif-wg@w3.org
Bijan wrote: >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. ...or that it was just mis-scribed. Others who were present for that session should look over what I wrote for mistakes or omissions. -Evan
Received on Thursday, 15 December 2005 17:41:29 UTC