- From: Michael Kifer <kifer@cs.sunysb.edu>
- Date: Mon, 12 Dec 2005 19:29:26 -0500
- To: "Evan K. Wallace" <ewallace@cme.nist.gov>
- Cc: public-rif-wg@w3.org
> Attached is a slightly modified version of the SW compatibility breakout notes > in PDF form. I added a key for the labels I used for the speakers. > > -Evan I have a Q regarding one of the remarks that Bijan made (according to the notes). Posting here because there might be wider interest in this. 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. --michael
Received on Tuesday, 13 December 2005 00:29:43 UTC