Re: [all] OWL and RDF compatibility scribles

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