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Re: Rule-based approach to conclude owl:intersectionOf

From: Jeremy Wong 黃泓量 <50263336@student.cityu.edu.hk>
Date: Tue, 05 Apr 2005 21:51:57 +0800
To: Chris Purcell <cjp39@cam.ac.uk>
Cc: semantic-web@w3.org
Message-id: <000001c539e6$bfa06b70$0401a8c0@wongkjo9u38gzb>

Oh my God.. i'd not make mistake again if it's in set..

CEXT(S(#X)) = {<#A>}
CEXT(S(#Y)) = {<#A>,<#B>}
CEXT(S(#Z)) = {<#A>,<#C>}
i.e.
<#A> rdf:type <#X> , <#Y> , <#Z> .
<#B> rdf:type <#Y> .
<#C> rdf:type <#Z> .
=>
<#X> rdfs:subClassOf <#Y> , <#Z> .
=>
<#X> owl:intersectionOf (<#Y>,<#Z>) .

I admit that this kind of inference requires a condition that the collection 
of facts is complete. Otherwise the inference results may be ruined if a 
fact like <#B> rdf:type <#X> is asserted. However, it is not a too bad 
interpretation because the OWL interpretation still satisifies the RDF graph 
above.

In addition, my main concern is the use of the universal quantification and 
the existential quantification. It is because N3 Rules cannot express the 
inference described in the above example. My work of rules shows that N3 
Rules is very weak to model OWL restrictions, anyway. I hope to discuss or 
to find out the use of the quantification facilities so that the rule-based 
approach becomes more powerful as expected.

:)
Jeremy

----- Original Message ----- 
From: "Chris Purcell" <cjp39@cam.ac.uk>
To: "Jeremy Wong 黃泓量" <50263336@student.cityu..edu.hk>
Cc: <semantic-web@w3.org>
Sent: Tuesday, April 05, 2005 8:20 PM
Subject: Re: Rule-based approach to conclude owl:intersectionOf


>> <#A> rdf:type <#X> .
>> <#B> rdf:type <#X> , <#Y> .
>> <#C> rdf:type <#X> , <#Z> .
>>
>> =>
>>
>> <#X> rdfs:subClassOf <#Y> , <#Z> .
>
> X = { A, B, C }, Y = { B } and Z = { C }. X is not a subclass of either Y 
> or Z, but the other way around.
>
> ----
>
> Assuming you had said
> <#Y>, <#Z> rdfs:subClassOf <#X>
> I would still have to disagree with you. From the RDF Concepts and 
> Abstract Syntax document:
>
> To facilitate operation at Internet scale, RDF is an open-world framework 
> that
> allows anyone to make statements about any resource.
>
> In general, it is not assumed that complete information about any resource 
> is
> available.
>
> Your conclusion is that, because every instance of Y **that you know of** 
> is also an instance of X, that this holds in general. However, the 
> following statement could also hold:
> <#D> rdf:type <#Z>
> On the face of it, using the same reasoning, we now "know" that Z is *not* 
> a subclass of X. But adding yet another statement,
> <#D> rdf:type <#X>,
> restores our "conclusion".
>
> In essence,
> <#Y> rdfs:subClassOf <#X>
> states that Y will always be a subclass of X, regardless of what 
> additional information we learn, and we therefore cannot deduce it from a 
> few instances of the use of X and Y.
>
> Chris
>
> 
Received on Tuesday, 5 April 2005 14:18:59 UTC

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