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Agenda-2010-02-24

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  •  Date of Call: Wednesday February 24, 2010
  • Time of Call: 18:00 UK, 13:00 (East US)
  • Dial-In #: +1.617.761.6200 (Cambridge, MA)
  • Dial-In #: +33.4.89.06.34.99 (Nice, France)
  • Dial-In #: +44.117.370.6152 (Bristol, UK)
  • Participant Access Code: 26631
  • IRC Channel: irc.w3.org port 6665 channel #sparql-ent ([irc:irc.w3.org:6665/sparql-ent])
  • Duration: 60 minutes
  • Chair: Birte Glimm
  • Scribe: ?
  • Link to Agenda: http://www.w3.org/2009/sparql/wiki/Agenda-2010-02-24


  • Admin
    • Do we need a scribe?
  • General entailment regimes issues
    • Should we have a finite vocabulary from which bindings can be taken for all variables and not just the ones in subject position. This allows for defining the scoping graph as graph equivalent to the active graph even in the case of an inconsistency and would mean a modified C2 condition.
      • Current C2 in PWD:
 (C2) Each variable x that occurs in the subject position of a triple in BGP is such that sk(μ(x)) occurs in sk(SG).

Proposed C2: 

 (C2) For each variable x in V(BGP), sk(μ(x)) occurs in sk(SG) or in Vocab.

Here vocab is defined as the reserved vocabulary for the entailment regime (e.g., the RDF vocabulary for RDF entailment) minus terms of the form rdf:_n with n in {1, 2, …}.

  • RIF issues
    • 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? Will there be something like rif:import?
    • 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?
    • 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))
    • How are blank nodes defined in RIF? Will skolemization/mapping to RIF local symbols work as for the other regimes?
    • Not all RIF dialects are based on a model-theory (e.g., RIF PRD), so they do not come with an entailment relation, but have a procedural semantics. Can we still use the procedural semantics to define something like an entailment regime?
    • Which RIF profiles should be included? Only RIF Core? Does RIF Core coincide with OWL RDF-Based or Direct Semantics? How many profiles are there?
    • What effects do the non-monotonic features of some RIF dialects have? E.g., RIF PRD and (anticipated) RIF dialects with default negation. How does that interact with SPARQL's non-monotonic features? This probably affects issue-43: Should entailment-regimes be declared over the whole dataset or individual graphs?
    • RIF production rules: it is no even clear how conjunctive queries work.
    • What is our timeline for RIF?
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