- From: Bob MacGregor <bmacgregor@siderean.com>
- Date: Tue, 22 Mar 2005 09:29:20 -0800
- To: andy.seaborne@hp.com
- CC: Dan Connolly <connolly@w3.org>, public-rdf-dawg-comments@w3.org
Andy, >> >> <clip>. First, I am assuming that the >> following query returns no bindings: >> >> SELECT ?x ?y >> WHERE { ?book dc10:title ?x } >> >> I shouldn't since it doesn't refer to OPTIONAL or UNION within the >> query, and the >> spec cites those as prerequisites for allowing unbound values. > > > Could you please say where in the spec you found text to draw that > conclusion? It is not true. > > It says in 2.1 > > """ > Optional matches and alternative matches may leave some variables > unbound (see the bound test). > """ > which is true about solutions to patterns; the text is not about > SELECT results. The impression that I am getting is that the committee is unaware how unorthodox the semantics is for SPARQL. I was using Occam's razor, assuming that if the language is designed to leave variables unbound, then it would say that up front. The language you cite above is the only language that speaks directly to this issue. The document contains no examples like the one up above. > > > The query > > SELECT ?x ?y > WHERE { ?book dc10:title ?x } > > can return bindings - it's a projection of a query solutions involving > ?x and ?book. > This is a horrendous decision by the committee. The above query ought to be flagged as illegal. Given that RDF is basically a small subset of FOL, its not at all clear to me why you are inventing a brand new semantics that does not resemble any of the mainstream logic languages. Regards, Bob
Received on Tuesday, 22 March 2005 17:29:58 UTC