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Re: [OK] Re: [OK?] Re: comments on "SPARQL Query Language for RDF"

From: Enrico Franconi <franconi@inf.unibz.it>
Date: Tue, 7 Mar 2006 19:35:27 +0100
Message-Id: <D102D27E-D288-4687-9E9D-88269E532698@inf.unibz.it>
Cc: eric@w3.org, connolly@w3.org, public-rdf-dawg-comments@w3.org
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>

On 7 Mar 2006, at 17:12, Peter F. Patel-Schneider wrote:
>> Ah. Well, for (this version of) SPARQL the scoping set contains  
>> exactly the
>> URIs, the Literals, and the bnodes from the scoping graph. It is a  
>> theorem that
>
> I don't see any such theorem in the documents.
>
>> under these restrictions the definitions given in 2.5 uniquely  
>> identify the answer
>> set - modulo renaming of bnodes - such that the answer set is  
>> exactly the
>> outcome of the homomorphisms between the query and the scoping graph.

 From section 2.5.2:

"A pattern solution can then be defined as follows: to match a basic  
graph pattern under simple entailment, it is possible to proceed by  
finding a mapping from blank nodes and variables in the basic graph  
pattern to terms in the graph being matched; a pattern solution is  
then a mapping restricted to just the variables, possibly with blank  
nodes renamed. Moreover, a uniqueness property guarantees the  
interoperability between SPARQL systems: given a graph and a basic  
graph pattern, the set of all the pattern solutions is unique up to  
blank node renaming."

cheers
--e.

Received on Tuesday, 7 March 2006 18:35:56 GMT

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