- From: Michael Schneider <schneid@fzi.de>
- Date: Tue, 26 Jul 2011 14:03:34 +0200
- To: <public-rdf-dawg-comments@w3.org>
Dear all! Document: SPARQL 1.1 Entailment Regimes State: LCWD In Section 1.3, condition 1, the specification of "entailment regimes" states: 1. A subset of RDF graphs called well-formed for the regime I believe that this condition is not sufficient for all entailment regimes in the document. Rational: --------- Take, for example, the following queried graph O and the (ground) BGP O1: O = { :p rdf:type owl:TransitiveProperty . } O1 = { :p rdf:type owl:AsymmetricObjectProperty . } Under the OWL 2 DL syntax [1], both O and O1 are syntactically valid ontologies (in RDF graph form), so they meet condition 1 for the OWL 2 Direct Semantics Entailment Regime. However, the entailment query "(O, O1)" is /not/ valid, as the combination of both graphs hurts the global restrictions in Chap. 11 of [1]: transitive properties must not be asymmetric properties. This is explained at the end of Chap. 3 of [2]: For ontology equivalence to be decidable, O1 needs to satisfy this restriction w.r.t. O and vice versa. (I believe that this condition of the Direct Semantics should not be restricted to /equivalence/, but is also needed for entailment). So, I believe that a entailment query "(O, O1)" has to be disallowed for the OWL 2 Direct Entailment Regime, at least if this regime is restricted to the OWL 2 DL syntactic fragment of OWL 2. Proposal: --------- Instead, I suggest, to change the condition as follows: 1. A set of /pairs of RDF graphs/ called well-formed for the regime In addition, in the tables for all entailment regimes, the row "Legal Graphs" should be replaced by "Legal Graph Pairs" or something like "Legal Entailment Queries", with the corresponding texts being updated. Final Note: ----------- If, against my current understanding, the OWL 2 Direct Entailment Regime is meant to be applicable to the full OWL 2 Structural Specification [1], and not only to the OWL 2 DL fragment with the global constraints to retain decidability (and other restrictions), then my comment is moot. But then, the document should be carefully checked that there is really no dependency on the OWL 2 DL fragment anywhere else. [1] http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/ [2] http://www.w3.org/TR/2009/REC-owl2-direct-semantics-20091027/ Best regards, Michael -- Dipl.-Inform. Michael Schneider Research Scientist, Information Process Engineering (IPE) Tel : +49-721-9654-726 Fax : +49-721-9654-727 Email: michael.schneider@fzi.de WWW : http://www.fzi.de/michael.schneider ============================================================================== FZI Forschungszentrum Informatik an der Universität Karlsruhe Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe Tel.: +49-721-9654-0, Fax: +49-721-9654-959 Stiftung des bürgerlichen Rechts Stiftung Az: 14-0563.1 Regierungspräsidium Karlsruhe Vorstand: Dipl. Wi.-Ing. Michael Flor, Prof. Dr. rer. nat. Ralf Reussner, Prof. Dr. rer. nat. Dr. h.c. Wolffried Stucky, Prof. Dr. rer. nat. Rudi Studer Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus ==============================================================================
Received on Tuesday, 26 July 2011 12:04:13 UTC