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Re: Proposed change to the OWL-2 Direct Semantics entailment regime

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Tue, 30 Nov 2010 14:27:51 +0000
Cc: Enrico Franconi <franconi@inf.unibz.it>, SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <10977582-0FBB-4AE8-8991-92F26EADDD80@cs.man.ac.uk>
To: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
On 30 Nov 2010, at 14:17, Birte Glimm wrote:
[snip]
> I can see some of your points, but a) you can always rewrite your
> queries to use complex OWL concepts with existential if you want to
> capture the semantics and b) I agree with Bijan's point here that
> although I did my PhD on queries with non-distinguished variables, I
> could never find any convincing real example where you would need the
> real existential meaning and I never managed to find a user who needed
> that even if they uderstood the intricacies of non-distinguished
> variables. I also talked with others here in Oxford, at ISWC, and I
> asked for feedback regarding this issue in my ISWC talk about the ent.
> regimes, but nobody came up who said that we should change the way it
> is.

Just to emphasize, this was with there being an implementation for people to play with that was Web accessible. It's still live in fact:
	http://www.mindswap.org/2003/pellet/demo.shtml

Indeed, here's a classic example:
	http://bit.ly/hWolmm

> Speaking as HermiT implementor, Ian, Boris, and I prefer the current
> regime and it would be even better if even RDF makes an official move
> to treating bnodes as constans that don't have a particular name,
> rather than as existential variables.

Oh yes.

> I think a spec is about making these decisions, so we should leave
> these things up to choice by allowing both and I to me it is also

This was rather garbled to me.

> important to not let OWL Drect Semantics diverge too much from the
> rest of SemWeb languages.


There's two versions of this: Not diverging from *specs* and not diverging from *practice*.  I think the latter trumps the former.

Cheers,
Bijan.
Received on Tuesday, 30 November 2010 14:28:08 GMT

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