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Re: "OWL" Entailment

From: Bijan Parsia <bparsia@cs.manchester.ac.uk>
Date: Sat, 9 May 2009 18:03:48 +0100
Cc: Bijan Parsia <bparsia@cs.man.ac.uk>, SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <2A42D83C-70E5-4218-93BD-771466011C4B@cs.manchester.ac.uk>
To: Steve Harris <steve.harris@garlik.com>
On 8 May 2009, at 11:13, Steve Harris wrote:

> On 6 May 2009, at 18:14, Bijan Parsia wrote:
>> 4) Controlling variable range (related to 1)
>> In OWL systems (such as Pellet, RacerPro, and KAON2) there are two  
>> kinds of variables "distinguished" and "non-distinguished" which  
>> are distinguishable by what sorts of bindings they allow: names  
>> only (and maybe "static" bnodes) or arbitrary elements of the  
>> domain. (See around slide 24 of <http://www.cs.man.ac.uk/~bparsia/2006/row-tutorial/index.html 
>> >.) It's good to allow for both sorts since distinguished variables  
>> are much cheaper to compute but non-distinguished variables get you  
>> more answers.
> Waaay out of my depth here, but would something like:
>  FILTER(isIRI(?distinguished))  or  FILTER(!isBlank(?distinguished))
> be sufficient to capture this?

*If* one had bnodes as bindings standing for (possibly computed)  
arbitrary elements of the domain *and* one didn't want bnodes handled  
as I think we would prefer them to be, then pretty much :)

We already have syntax for non-distinguished variables...blank nodes  
in the query:

The main issue is whether to identify a "profile" that disallowed non- 
distinguished variables (as that profile is fairly common).

> I'm not quite sure where/how OWL names behave differently to URIs.

No differently, really.

> FWIW, we use some similar optimisations to cut the search space in  
> our SPARQL engine, and it's quite easy to spot, as long as the user  
> doesn't go out of their way to hide it.


Received on Saturday, 9 May 2009 17:04:24 UTC

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