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Re: owl:allValuesFrom inference

From: Uli Sattler <sattler@cs.man.ac.uk>
Date: Thu, 25 Jun 2009 14:12:18 +0100
Cc: Owl Dev <public-owl-dev@w3.org>
Message-Id: <3ACF3E41-B187-476F-8186-4EB045D8436F@cs.man.ac.uk>
To: Bernhard Schandl <bernhard.schandl@univie.ac.at>

On 25 Jun 2009, at 11:12, Bernhard Schandl wrote:

> Hi,
>> What you want to say is that *if something is madeby a Man (and  
>> possibly by some other things), then this something is a  
>> ThingMadeByMan.
> exactly.
>> So there direction of the implication needs to go the other way  
>> round an you need existential (someValues) restriction... in  
>> Manchester Syntax:
>> Class: ThingMadeByMan
>>  EquivalentTo:
>>    madeBy some Man
> I'm not too familiar with Manchester Syntax, is this equivalent to  
> (n3):
> ex:ThingMadeByMan
>   a owl:Restriction ;
>   owl:onProperty ex:madeBy ;
>   owl:someValuesFrom ex:Man ;
> .
> ... because I tried this one, but stil the implication

hm, I'm not familiar with n3 syntax -- but i know that, in OWL, we  
have both "SubClassOf" and "EquivalentClass" statements -- and that it  
is important to distinguish the two...namely, if you say that X and Y  
are equivalent classes, then this has the same consequences as saying  
that X is a subclass of Y and Y is a subclass of X.

Now, in your example, you want to infer *from* something being made by  
men that something is a ThingMadeByMan...for which you need the  
implication 'from right to left'...or in both directions.

>> This axiom together with your 2 assertions above about Bart and  
>> Something should then imply that Something is ThingMadeByMan
> is not derived by Pellet. :-(
> Also I wonder what a reasoner can actually infer from  
> owl:someValuesFrom -- as far as I can tell from the spec [1] it can  
> actually only be used to check the consistency of a model, but not  
> to infer new facts, since the reasoner cannot decide which of the  
> (possibly many) values of the property is an instance of the  
> specified class.

I am not sure where this impression came from -- but its wrong, you  
can infer new facts: did you try your example? In your example, you  
have *stated* that Bart is a Man and that Something is madeby Bart;  
hence we (and the reasoner, too) can infer that Something is madeBy a  
Man and thus, if we also defined (!) things madeBy a Man to be    
ThingMadeByMan, then we (and the reasoner) can infer that Something is  
a ThingMadeByMan.

Cheers, Uli

> Am I missing something here?

> Best, Bernhard
Received on Thursday, 25 June 2009 13:12:48 UTC

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