- From: Eric Prud'hommeaux <eric@w3.org>
- Date: Tue, 19 Sep 2006 15:43:30 +0200
- To: dawg mailing list <public-rdf-dawg@w3.org>
ACTION: ericP to send mail describing how [VTV] and [BTV] (posted
[PST]) illustrate basic graph matching conflicts between
[LC1] and [LC2] semantics
<http://www.w3.org/2006/09/12-dawg-minutes#action01>
recorded in http://www.w3.org/2006/09/12-dawg-irc#T14-36-27
In [LC1], basic graph pattern matching was defined in terms of
subgraphs. As I read [LC2],
[[
Definition: Basic Graph Pattern equivalence
Two basic graph patterns are equivalent if there is a bijection M
between the terms of the triple patterns that maps blank nodes to
blank nodes and maps variables, literals and IRIs to themselves, such
that a triple ( s, p, o ) is in the first pattern if and only if the
triple ( M(s), M(p) M(o) ) is in the second.
]]
we have at least an optional leaning. This is supported by the Pellet
demo. For [VTV],
[[
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT ?who ?type
WHERE { ?who rdf:type ?type }
]]
Pellet finds 5 nodes of type foaf:Person. When ?who is projected away,
Pellet reports 1 foaf:Person.
Slightly related:
I was asked by DanC to produce illustrative test cases for all the
design options presented in the draft. I would especially appreciate
help with tests for this issue.
[VTV] http://www.w3.org/2001/sw/DataAccess/tests/#rdfsemantics-var-type-var
[BTV] http://www.w3.org/2001/sw/DataAccess/tests/#rdfsemantics-bnode-type-var
[PST] http://www.w3.org/mid/20060814121827.GC6336@w3.org
[LC1] http://www.w3.org/TR/2005/WD-rdf-sparql-query-20050721/#BasicGraphPatternMatching
[LC2] http://www.w3.org/TR/2006/WD-rdf-sparql-query-20060220/#BasicGraphPatternMatching
--
-eric
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Received on Tuesday, 19 September 2006 13:42:27 UTC