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

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:-(

Ivan


>> Presumably, making axiomatic triples be part of OWL RL (Full) would 
>> mean extending the rule set so that it would generate such triples. 
>> There could be a very large (perhaps even infinite) number of such 
>> triples. This might be a serious burden on implementations and lead to 
>> a significant degradation in performance.
> 
> 
> 
>> "Entailment" might be not the right term here, because it is probably 
>> more
>> typically used in the context of model-theoretic semantics. I prefer 
>> to speak about "derivations".
> 
> We need to figure out and use a common language or make the appropriate 
> language visible in the specification  if it is missing.
> 
> -Alan
> 
>>
>>> -Alan
>>
>> Cheers,
>> Michael
>>
>> -- 
>> Dipl.-Inform. Michael Schneider
>> FZI Forschungszentrum Informatik Karlsruhe
>> Abtl. Information Process Engineering (IPE)
>> Tel  : +49-721-9654-726
>> Fax  : +49-721-9654-727
>> Email: Michael.Schneider@fzi.de
>> Web  : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555
>>
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>> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe
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>>
> 

-- 

Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
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