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rq25 edits to 3 RDF Term Constraints and 11 Testing Values

From: Eric Prud'hommeaux <eric@w3.org>
Date: Mon, 12 Mar 2007 00:29:21 -0400
To: "Seaborne, Andy" <andy.seaborne@hp.com>
Cc: my dawgs <public-rdf-dawg@w3.org>
Message-ID: <20070312042921.GB21623@w3.org>
Examining these sections for conformance implications, I made the
following changes to revision 1.41:

I changed §3 RDF Term Constraints [TC] from
Graph pattern matching creates bindings of variables to RDF terms. It
is possible to restrict solutions by constraining the RDF terms that
match a given query. A value constraint is a boolean-valued
expression; there is a set of functions & operators in SPARQL for
constraints. In addition, there is an extension mechanism to provide
access to functions that are not defined in the SPARQL language.

A constraint may lead to an error condition when testing some RDF
term. The exact error will depend on the constraint: for example, in
numeric operations, solutions with variables bound to a non-number or
a blank node will lead to an error. Any potential solution that causes
an error condition in a constraint will not form part of the final
results, but does not necessarily cause the query to fail.


Graph pattern matching produces a solution sequence, where each
solution has a set of bindings of variables to RDF terms. SPARQL
FILTERs restrict solutions to those for which the filter expression
evaluates to TRUE.

This section provides an informal introduction to SPARQL FILTERs;
their semantics are defined in Section 11. Testing Values. The
examples in this section share one input graph.


There is no other mention of errors in this section so the user need
not be troubled by them until §11 Testing Values [TV]. I think one
forward reference to §11 makes for the easiest reading.

I added a sentence so that §11 Testing Values [TV] ¶1 emds with:

Effective boolean values are defined in section 11.2.2 Effective
Boolean Value and errors are defined in XQuery 1.0: An XML Query
Language [XQUERY] section 2.3.1, Kinds of Errors. These errors have
no affect outside of FILTER evaluation.

This is to clarify that these errors have no impact on protocols or
APIs, only on the mapping from query and data to results as defined
by the SPARQL language.

[TC] http://www.w3.org/2001/sw/DataAccess/rq23/rq25#termConstraint
[TV] http://www.w3.org/2001/sw/DataAccess/rq23/rq25#tests

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Received on Monday, 12 March 2007 04:29:28 UTC

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