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Re: Simple modelling of a temporal sequence

From: Matthew Graham <mjg@cacr.caltech.edu>
Date: Mon, 31 Aug 2009 22:59:43 -0700
Cc: <public-owl-dev@w3.org>
Message-Id: <CCE7CE84-9D37-47A7-9A66-C7BB7F82FC97@cacr.caltech.edu>
To: "Michael Schneider" <schneid@fzi.de>
Hi Michael,

I'm using Protege 4.0 with Pellet as the reasoner.

Can I place a universality restriction on a transitive property in OWL  
DL? 4-cell subClassOf (after only 2-cell)

Would this give me the result I want? If not, what is the recommended  
way to do this of modelling?

	Cheers,

	Matthew


On Aug 31, 2009, at 10:47 PM, Michael Schneider wrote:

> Hi Matthew!
>
> It sounds to me that you want to put an existential restriction on a
> transitive property ("after"). Since you refer to OWL DL below, let
> me say that doing so is not allowed in OWL DL, i.e. your ontology
> is not a syntactic valid OWL DL ontology. See
>
> <http://www.w3.org/TR/owl-semantics/syntax.html#transitivity_side>
>
> So you should not expect any OWL DL reasoner to do any reasoning
> at all on your ontology, but rather expect it to signal a syntax
> error.
>
> Now, you did not tell us which reasoner you are using. For example,
> if you are using Pellet, then note that this reasoner actually
> performs reasoning in this situation, but only after first dropping
> the transitivity axiom from "after". See
>
> <http://clarkparsia.com/pellet/faq/owl-full/>
>
> """
> OWL-DL Restriction: OWL DL requires that no cardinality constraints
> (local nor global) can be placed on transitive properties or their
> inverses or any of their superproperties.
>
> Pellet Restriction: Pellet requires this restriction. Any
> transitivity axiom violating these restrictions are ignored
> (cardinality restrictions are not ignored).
> """
>
> Cheers,
> Michael
>
> Matthew Graham wrote:
>
>> Hi,
>>
>> I'm trying to model a simple temporal sequence with a class called
>> Stage which has 5 subclasses: 2-cell, 4-cell, 8-cell, 16-cell and 32-
>> cell.
>>
>> There are also four object properties: startStage, endStage, before
>> and after. before and after are defined to be transitive and inverse
>> to each other and with domain Stage and range Stage.
>>
>> 32-cell is then defined to be: after some 16-cell; 16-cell is defined
>> as: after 8-cell; etc.
>>
>> Finally I declare an individual called ptype1 with startStage some 4-
>> cell.
>>
>> I then run the reasoner on the ontology and try the DL Query:
>> startStage some (before 8-cell)
>>
>> This does not return ptype1. Why not? Do I have to explicitly state
>> the inverse relationships, e.g. 16-cell before some 32-cell, as  
>> well -
>> why are these not inferred during reasoning?
>>
>> 	Cheers,
>>
>> 	Matthew
>
> --
> Dipl.-Inform. Michael Schneider
> Research Scientist, Dept. Information Process Engineering (IPE)
> Tel  : +49-721-9654-726
> Fax  : +49-721-9654-727
> Email: michael.schneider@fzi.de
> WWW  : http://www.fzi.de/michael.schneider
> = 
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Received on Tuesday, 1 September 2009 06:00:26 GMT

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