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Re: Issues with evaluating optional: Commutativity of AND

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Sat, 14 Oct 2006 15:10:40 +0100
Message-Id: <24E23B67-56A9-49F3-B9BF-4701F961DA42@cs.man.ac.uk>
Cc: Fred Zemke <fred.zemke@oracle.com>, public-rdf-dawg@w3.org
To: Bijan Parsia <bparsia@cs.man.ac.uk>

Just to be crystal clear since it's evidently an issue easy to get  
confused on, do you think that for two arbitrary graph patterns G1  
and G2, should

	Join(G1, G2) = Join(G2, G1).

Where Join/2 is inner/natural/standard join.

If so, should the basic connective of graph patterns in SPARQL be Join?

My answers are Yes and Yes. This is the answer in SCS. From what I  
can glean, Andy is in favor a different basic connective (where the  
above relation isn't always true). (I presume he'd agree that Join  
obeys the above equality).

Cheers,
Bijan.
Received on Saturday, 14 October 2006 14:10:54 GMT

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