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[TF-ENT] 24th Feb teleconf summary

From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
Date: Wed, 24 Feb 2010 21:49:35 +0000
Message-ID: <492f2b0b1002241349i607b41f4oe98e0bbe1480d382@mail.gmail.com>
To: SPARQL Working Group <public-rdf-dawg@w3.org>
Hi all,
Below a short summary for the points we discussed in today's teleconf.

* General entailment regimes issues

There was no clear consensus whether the modified C2 should be used.
Topic is discussed further by mail (see my separate follow-up email on
this).

* RIF issues
 o Will/should RIF be marked as "at risk" depending on the RIF WG note
   about the RIF-to-RDF mapping? What is the status of the RIF to RDF
   mapping?

Not necessary. RIF hopefully is a REC within ~2 month. We'll see how
far we are when we go to last call.

 o Will there be something like rif:import?

Most likely SPARQL will define a special keyword for this. E.g., a
graph containing a triple
[] sparql:useRuleSet URI_to_rule_set
will have special meaning for a system that uses RIF entailment and
the system will treat this similar to an owl imports directive and
attempt to load rules from
 the document at  URI_to_rule_set.

 o Entailment regimes have to define which graphs the accept. Will the RIF
   entailment regime work with all RDF graphs? Different lists in RDF and
   RIF?

For now we assume yes.

 o Will each rule set be an entailment regime, e.g., the SD says something
   like: myEndpoint sd:EntailmentRegime <http://example.org/myRules.rif>?
   Or is there a suitable RIF entailment relation (RIF+RDF semantics) and
   one specifies a rule set in a from clause or in the data set? Which RIF
   profiles does that cover? This might affect the condition on extensions
   to BGP matching that requires that
   SG E-entails (SG union P1(BGP1) union ... union Pn(BGPn))

Not necessary if there is some form of import, e.g., as the one described above.

 o How are blank nodes defined in RIF? Will skolemization/mapping to RIF
   local symbols work as for the other regimes?

That seems to be no problem.

Then we discussed how we can guarantee finiteness in different RIF
dialects. The strongly safe part of RIF Core (strongly safe is
informative in the RIF spec) seems to be easy (one can build a finite
Herbrand model, partial closure).
The other dialects are not very straightforward. Sandro suggested
dropping the condition of finiteness and sees no formal problems since
that will not invalidate existing implementations. Other are more
worried about changing the SPARQL 1.0 conditions. So far, we'll
continue the discussion about how to achieve finite answers in next
week's teleconf.

Birte

--
Dr. Birte Glimm, Room 306
Computing Laboratory
Parks Road
Oxford
OX1 3QD
United Kingdom
+44 (0)1865 283529



-- 
Dr. Birte Glimm, Room 306
Computing Laboratory
Parks Road
Oxford
OX1 3QD
United Kingdom
+44 (0)1865 283529
Received on Wednesday, 24 February 2010 21:50:07 GMT

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