- From: Michael Schneider <schneid@fzi.de>
- Date: Fri, 2 Jul 2010 11:26:32 +0200
- To: "Pat Hayes" <phayes@ihmc.us>
- Cc: "Linked Data community" <public-lod@w3.org>, "Semantic Web" <semantic-web@w3.org>
Pat Hayes wrote: >Just to clarify, this is a purely syntactic restriction. Allowing >literals in subject position would require **no change at all** to the >RDF semantics. Indeed. And this is probably one of the reasons why several RDF-related standards have already adopted literal subjects. Some examples: * For the OWL 2 RDF-Based Semantics, being an extension of the RDF Semantics, it has been explicitly allowed (in the "MAY" sense) to apply it to "generalized RDF", where literals and bNodes may occur in any position of a triple: <http://www.w3.org/TR/owl2-rdf-based-semantics/#topic-ont-generalrdf> (However, OWL 2 Full is still defined to be the language that consists of the RDF-Based Semantics and the official RDF Syntax, i.e. where subjects are not allowed to be literals.) * The OWL 2 RL/RDF Ruleset also allows for generalized RDF, see the second paragraph of <http://www.w3.org/2007/OWL/wiki/Profiles#Reasoning_in_OWL_2_RL_and_RDF_Grap hs_using_Rules> * The RIF RDF and OWL Compatibility specification (just became a W3C Recommendation) also uses generalized RDF, see the note at <http://www.w3.org/TR/2010/REC-rif-rdf-owl-20100622/#note-generalized-rdf-gr aphs> and the definitions at <http://www.w3.org/TR/2010/REC-rif-rdf-owl-20100622/#RDF_Vocabularies_and_Gr aphs> * SPARQL 1.1 (still work in progress) allows literal subjects in Triple Patterns: <http://www.w3.org/TR/sparql11-query/#defn_TriplePattern> I could imagine that this list of important technologies allowing for literal subjects will grow over time, and maybe there even exist some more today that I missed. If RDF2 would also adopt generalized RDF, all these RDF-dependent standards could then be updated by dropping all these "MAY"s and similar statements. 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, Az 14-0563.1, RP Karlsruhe Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael Flor, Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus =======================================================================
Received on Friday, 2 July 2010 09:27:12 UTC