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Re: ACTION-178: What is ISSUE-116 (Axiomatic Triples for OWL R) about?

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Tue, 12 Aug 2008 13:22:14 -0400
Message-Id: <E4C2BFAE-B12C-44F0-A490-6087FFE7FAFC@gmail.com>
Cc: public-owl-wg@w3.org
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>


On Aug 12, 2008, at 11:31 AM, Peter F. Patel-Schneider wrote:

>
> From: Alan Ruttenberg <alanruttenberg@gmail.com>
> Subject: Re: ACTION-178: What is ISSUE-116 (Axiomatic Triples for  
> OWL R) about?
> Date: Tue, 12 Aug 2008 11:22:40 -0400
>
>> On Aug 12, 2008, at 11:16 AM, Ivan Herman wrote:
>>
>>> Alan Ruttenberg wrote:
>>>> On Aug 12, 2008, at 11:02 AM, Michael Schneider wrote:
>>>>> Alan Ruttenberg wrote:
>>>>>
>>>>>> Is the assumption that in OWL R/Full that the only way in  
>>>>>> which one
>>>>>> determine entailments is to forward chain rules and then look in
>>>>>> the resultant triples for it?
>>>>>
>>>>> It's not an "execution semantics". Instead, there has to *exist* a
>>>>> finite sequence of rule applications, which leads from the LHS  
>>>>> to the RHS
>>>>> (or an upper graph of the RHS).
>>>> OK. I'm then confused by Ian's comment about generating infinite
>>>> numbers of triples:
>>>
>>> But his comment _was_ justified. In
>>>
>>> http://www.w3.org/TR/rdf-mt/#RDFINTERP
>>>
>>> the number of axiomatic triples is infinite indeed, due to the  
>>> rdf:_i
>>> terms. Herman ter Horst's trick of keeping it finite for a specific
>>> graph tries to get around that problem and thereby making it  
>>> possible to
>>> do, eg, a forward chaining on a specific graph (with the caveat that
>>> PFPS just referred to in another mail:-(
>>
>> Yes, but my question to Michael was to this point.  From what he  
>> says I
>> don't see that the theoretical existence of an infinite number of
>> triples necessitates their materialization by forward chaining. There
>> are other methods of using rules.
>>
>> -Alan
>
> Which of the other methods of using rules are germane to this  
> discussion?

I am trying to understand the underlying assumptions in this  
discussion. If no other method of rule applications than forward  
chaining are being considered and a solution to this issue should  
assume a forward chaining rule engine that would be useful  
information. What prompts the questions and comment were an earlier  
discussion in which it was mentioned that JENA used a combination of  
forward and backwards chaining.

Therefore your question is  one I would I would like answered as  
well, but I am not the one to answer it.

-Alan
Received on Tuesday, 12 August 2008 17:22:53 GMT

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