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Re: ISSUE-83 (Vipul): Property Chain Axiom: P1 o P2 => P2 o P1

From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
Date: Tue, 4 Dec 2007 09:47:04 +0000
Message-Id: <4866726B-9CD8-46EF-BAF2-D0987DB0E24E@comlab.ox.ac.uk>
Cc: <conrad.bock@nist.gov>, "'Kashyap, Vipul'" <VKASHYAP1@PARTNERS.ORG>, "'Jeremy Carroll'" <jjc@hpl.hp.com>, "'OWL Working Group WG'" <public-owl-wg@w3.org>
To: Uli Sattler <sattler@cs.man.ac.uk>

To summarise: This is not allowed in the existing syntax, it would  
lead to undecidability if it were allowed (even for very restricted  
language subsets), it is not supported by implementations and seems  
unlikely to be supported in the foreseeable future. I therefore  
propose to postpone it on these grounds.

Ian


On 3 Dec 2007, at 18:59, Uli Sattler wrote:

>
> Hi Conrad -
>
> On 3 Dec 2007, at 15:38, Conrad Bock wrote:
>
>>
>> Uli,
>>
>>>  makes reasoning undecidable (even R o S => T in general, ie,  
>>> without
>>>  the restrictions imposed by OWL 1.1 because it allows you to reduce
>>>  the intersection problem of contex-free languages to satisfiability
>>>  of concepts) ...
>>
>> Do you know of anyone working on restrictions that would make  
>> chains in
>> the "super" position (right hand side) decidable?
>>
>
> I don't know of anybody currently working on it, but we know that  
> it (having R o S => T o U)  makes reasoning undecidable in the  
> logic that
>
> - has only IntersectionOf an SomeValuesFrom restrictions (see  
> Baader, DL 2003, http://sunsite.informatik.rwth-aachen.de/ 
> Publications/CEUR-WS/Vol-81/baader.pdf)
>
> - has only intersectionOf and AllValuesFrom Manfred Schmidt-Schau .  
> Subsumption in KL-ONE is undecidable. In Ron J.
> Brachman, Hector J. Levesque, and Ray Reiter, editors, Proc. of the  
> 1st Int.
> Conf. on the Principles of Knowledge Representation and Reasoning  
> (KR'89),
> pages 421-431. Morgan Kaufmann, Los Altos, 1989.
>
> Cheers, Uli
>
>> Conrad
>>
>>>  On 30 Nov 2007, at 14:53, Kashyap, Vipul wrote:
>>>
>>>>
>>>>
>>>> Would be interested in on the ramifications on the complexity of
>>>> reasoning.
>>>>
>>>> ---Vipul
>>>>
>>>>> -----Original Message-----
>>>>> From: public-owl-wg-request@w3.org
>>>>> [mailto:public-owl-wg-request@w3.org] On Behalf Of Jeremy Carroll
>>>>> Sent: Friday, November 30, 2007 8:53 AM
>>>>> To: OWL Working Group WG
>>>>> Subject: Re: ISSUE-83 (Vipul): Property Chain Axiom: P1 o P2
>>>>> => P2 o P1
>>>>>
>>>>>
>>>>> OWL Working Group Issue Tracker wrote:
>>>>>>
>>>>>> ISSUE-83 (Vipul): Property Chain Axiom: P1 o P2 => P2 o P1
>>>>>>
>>>>>> http://www.w3.org/2007/OWL/tracker/issues/
>>>>>>
>>>>>> Raised by: Vipul Kashyap
>>>>>> On product:
>>>>>>
>>>>>> I would like support for the property chain axiom.
>>>>>> The use case is based on Alan Rector's example in the
>>>  DL Handbook
>>>>>>
>>>>>> Skin of the finger is part of the skin of the hand.
>>>>>> covers o part --> part o covers
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> ---Vipul
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> Interestingly, the constructs we already have, put this
>>>  into the OWL
>>>>> Full version of the language ...
>>>>>
>>>>> Jeremy
>>>>>
>>>>>
>>>>
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>>>
>>>
>>
>>
>
>
Received on Tuesday, 4 December 2007 09:47:21 GMT

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