- From: Pat Hayes <phayes@ihmc.us>
- Date: Sun, 6 Aug 2006 21:40:55 -0700
- To: Bijan Parsia <bparsia@cs.man.ac.uk>
- Cc: RDF Data Access Working Group <public-rdf-dawg@w3.org>
>It occurs to me that one way to manage the >distinguished/semidistinguished/nondistinguished mechanism a bit >more neatly would be to dispense with the distinction between BNodes >and query variables (except for spelling and syntactic restrictions >on placements) in queries, and force the range of the variables to >depend on the query form. That is, SELECT forces distinguished >variables, and ASK the rest. So there are no bnodes in SELECT patterns, if I follow you (?) That seems like a big handicap. > We could then allow variables to be listed in the "head" of the ASK >clause (as in the SELECT clause), so that the distinction between >semi and nondistinguished variables is merely projection/listing in >the head. This sounds very like one of the options we used in DQL, where an ASK was basically a SELECT with nothing selected. >You could list BNodes in the head just like other query variables, >or dispense with them altogether, or allow them to have their >present form, to wit, being dedicately non-distinguished. Actually I don't think that is their current role in SPARQL, if I understand what you mean by non-distinguished. >Unfortunately, while rather neat, it's not very practical, as people >are used to using SELECT as their query form (a la SQL) and, >especially in the RDF case, likely to want semi-distinguished >variables by default. Right. I would strongly oppose restricting variable bindings in RDF SPARQL: there is no computational need to do so, and it would make the answers incomplete for no good reason. Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 or (650)494 3973 home 40 South Alcaniz St. (850)202 4416 office Pensacola (850)202 4440 fax FL 32502 (850)291 0667 cell phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes
Received on Monday, 7 August 2006 04:41:10 UTC