Restructure definition of Basic Graph Pattern and pattern match (sec 2.4)

SPARQL language editor's draft rev 1.379
http://www.w3.org/2001/sw/DataAccess/rq23/

In section 2.4 the terms 'Pattern Solution', 'Query Solution' and
'Basic Graph Pattern' are defined,

The definition of Basic Graph Pattern includes what it means to match
against a graph. It would be better to create a separate definition
for this, called 'Graph Pattern Match'. The definition of 'Basic Graph
Pattern' can then be moved to the start of the section, and in any
case I think an explicit definition of pattern match, that links graph
patterns to solutions, is a lot clearer.

Also, the current definition of a match is imprecise. It uses the
notion 'entails' without specifying what that means. Is that simple
entailment, RDF(S) entailment, or an entirely different, more loose
form of entailment? I request instead using the notion of 'subgraph'
for defining a match.

Suggested definitions:

   Definition: *Basic Graph Pattern*

   A /basic graph pattern/ is a set of Triple Patterns.

   Definition: *Graph Pattern Match*

   A graph pattern /matches/ on a graph G with pattern solution S iff
   S(GP) is a non-empty subgraph of G.

Jeen
-- 
Jeen Broekstra          Aduna BV
Knowledge Engineer      Julianaplein 14b, 3817 CS Amersfoort
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tel. +31 33 46599877