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Re: subgraph/entailment

From: Enrico Franconi <franconi@inf.unibz.it>
Date: Mon, 19 Sep 2005 20:55:04 +0200
Message-Id: <641b8800a511601633a7f592f5597af8@inf.unibz.it>
To: Pat Hayes <phayes@ihmc.us>, Peter F. Patel-Schneider <pfps@research.bell-labs.com>, Ian Horrocks <horrocks@cs.man.ac.uk>, Bijan Parsia <bparsia@isr.umd.edu>, Dan Connolly <connolly@w3.org>, public-rdf-dawg-comments@w3.org

> From: Pat Hayes <phayes@ihmc.us>
> If one wishes to offer a query-answering service that does check 
> entailments, then the appropriate thing to do within the SPARQL 
> framework is to declare that one is matching queries against a 
> 'virtual graph' which is some kind of logical closure of the graph, 
> rather than the graph itself. But these are different graphs, note.

Sure, we clearly understand that.

> SPARQL does not require queries to be evaluated only against graphs 
> which are closed under some notion of entailment: it is 
> entailment-neutral (except, as noted above, regarding simple 
> entailment, which follows in effect as a structural consequence of the 
> very act of matching itself.) This is not an error or an omission, I 
> would emphasize, but a design decision.

Fine, we want just give a nice semantics to it, which characterises the 
current design decisions, but that also scales up to have general 
entailment based query answering. Our proposal accommodates the current 
"syntactic-driven" behaviour of SPARQL *and* an entailment based one. 
Whatever has been done so far is fine for us, we are just giving a 
general entailment based semantics to it, which makes SPARQL much more 
useful and semantically meaningful.
I'll send to the list our proposal later today.

Received on Monday, 19 September 2005 19:00:23 UTC

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