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

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 22 Mar 2006 09:48:12 -0500 (EST)
Message-Id: <20060322.094812.82629009.pfps@research.bell-labs.com>
To: franconi@inf.unibz.it
Cc: eric@w3.org, connolly@w3.org, public-rdf-dawg-comments@w3.org

From: Enrico Franconi <franconi@inf.unibz.it>
Subject: Re: [OK] Re: [OK?] Re: comments on "SPARQL Query Language for RDF" 
Date: Tue, 7 Mar 2006 19:35:27 +0100

> 
> 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.

This is a claim, not a theorem (with proof).

peter
Received on Wednesday, 22 March 2006 14:48:39 GMT

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