- From: Michael Schneider <schneid@fzi.de>
- Date: Tue, 26 Jul 2011 13:02:24 +0200
- To: <public-rdf-dawg-comments@w3.org>
Dear all! Document: SPARQL 1.1 Entailment Regimes State: LCWD The first paragraph in Chap. 6 "OWL 2 Direct Semantics Entailment Regime" states that variables are allowed in place of class names and property names. Nothing is said, however, about what the semantic consequences are of such enhanced flexibility. If one tries to conservatively extend the OWL 2 Direct Semantics [1] to support such queries, the only way I see is to do this by a translation into quantifying over variables for unary and binary relations (note that under the Direct Semantics, classes and properties are sets and binary relations, respectively). In other words, such a semantics goes beyond first-order logic (FOL). This is significant, as the OWL 2 Direct Semantics was designed as a fragment of standard FOL. I do not suggest to change the current specification, since I consider variables in class and property position to be useful. What I suggest is to make the "non-FOL issue" explicit in the document, to make implementers aware of it. I suggest to put such a discussion in Sec. 6.4, which is already dedicated to "Higher Order Queries", but does not treat this issue. [1] <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 11:03:05 UTC