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Re: putting entailment into SPARQL

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Fri, 16 Dec 2005 10:11:20 +0000
Message-ID: <43A292C8.70207@hp.com>
To: Pat Hayes <phayes@ihmc.us>
CC: "Eric Prud'hommeaux" <eric@w3.org>, RDF Data Access Working Group <public-rdf-dawg@w3.org>

Pat: specific question:

In 2.7, you suggest text

"""
Blank nodes in the results of a query are identical to those occurring in the 
dataset graphs ...
"""

Not sure about "identical".

A solution matches a basic graph by simple entailment so any bNode in the 
solution is not necesarily the same as the one corresponding one in the graph. 
  Together with the document scope of bNode labels in teh XML rsult format and 
in any RDF serialization, means that even if they were the same, you can't 
tell.  All that is transmitted is whether two bNodes in the document are the 
same or different.

Or have I missed something?

	Andy

>>
>>PS. One other rewording in section 2.7:
>>
>>"An application or client receiving the results of a query can tell 
>>that two solutions or two variable bindings differ in blank nodes but 
>>this information is only scoped to the results as defined in "SPARQL 
>>Variable Binding Results XML Format" or the CONSTRUCT result form."
>>//
>>SIMPLE CASE A:
>>"Blank nodes in the results of a query are identical to those 
>>occurring in the dataset graphs, but this information cannot be used 
>>by an application or client which receives these results, since all 
>>blank nodes in subsequent queries are treated as being local to that 
>>query. In effect, this means that information about co-occurrences of 
>>blank nodes may be treated as scoped to the results as defined in 
>>"SPARQL Variable Binding Results XML Format" or the CONSTRUCT result 
>>form."
>>
>>OR, complex case B with persistent bnodes:
>>
>>//"Blank nodes in the results of a query are identical to those 
>>occurring in the dataset graphs, and may be re-used in subsequent 
>>queries as persistent blank nodes. Servers which accept a query 
>>containing a persistent blank node must respect the identity of such 
>>blank node identifiers across multiple queries and answer bindings. 
>>In contrast, blank nodes which appear in queries as nonpersistent 
>>blank nodes are treated as being local to that query, and bear no 
>>relationship to occurrences of the same blank node in other queries 
>>or their answer bindings."
>>
Received on Friday, 16 December 2005 10:12:34 GMT

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