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On the functionalities of the OWL RL profile

From: Ivan Herman <ivan@w3.org>
Date: Mon, 25 Aug 2008 15:23:45 +0200
Message-ID: <48B2B261.6060206@w3.org>
To: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
CC: public-owl-wg Group WG <public-owl-wg@w3.org>
Ian,

I changed the subject line because this is not on the unification issue
and I do not want the tracker to pick it up...

This reflects some discussions we had with Boris but off-list. The
current OWL RL is relatively large, eg, if one looks at the rule set.
More to the point, it may add quite a number of extra triples to the
store (at least conceptually). Maybe it is worth looking at the
functionalities with a critical eye to see whether it is worth having
them there (although I am fully aware that this is difficult and a bit
subjective...).

The specific issue that came up is the possibility of having a reflexive
property. This leads to the

T(?p, rdf:type, owl:ReflexiveProperty)
T(?x, ?y, ?z) 	

=>

T(?x, ?p, ?x)
T(?y, ?p, ?y)
T(?z, ?p, ?z)

rule, ie, the existence of a single reflexive property would add a huge
number of triples to the triple set. Although this is technically
perfectly fine, I was wondering whether it is o.k. to have it there (of
course, one argument might be that if the user does not want this think
than, well, (s)he should not use it...). Boris, in a private mail, told
that reflexive properties are not necessary for OWL RL in general, he
just copied there in the first draft.

This may be the only example and, if so, we may just want to let it as
is. But it may be worth looking at the various features with a critical
eye to see if it is necessary to be there...

Just a thought. Maybe it is worth raising it as a separate issue.

Thanks

Ivan


Ian Horrocks wrote:
> 
> We (Alan and I) agreed that it would help to clarify this issue and to
> inform our discussion on Wednesday if the Profiles document [1] were
> updated to reflect the proposed "unification". This has now been done.
> It should be read in conjunction with the (draft) conformance
> definitions [2].
> 
> Regards,
> Ian
> 
> [1] http://www.w3.org/2007/OWL/wiki/Profiles
> [2] http://www.w3.org/2007/OWL/wiki/Conformance
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf


Received on Monday, 25 August 2008 13:24:18 GMT

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