Re: [all] OWL and RDF compatibility scribles

> 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