W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > December 2002

Re: Semantics doc now in shadow TR space

From: pat hayes <phayes@ai.uwf.edu>
Date: Mon, 16 Dec 2002 11:15:30 -0600
Message-Id: <p05111b04ba23b837f898@[]>
To: Graham Klyne <GK@NineByNine.org>
Cc: w3c-rdfcore-wg@w3.org

>Concerning:  http://www.coginst.uwf.edu/~phayes/RDF_Semantics_finalCall_2.html
>At 03:12 PM 12/15/02 -0600, pat hayes wrote:
>>Datatype clashes are the only inconsistencies recognized by this 
>>model theory. The definition of entailment means that a 
>>D-inconsistent graph D-entails any RDF graph; however, it will 
>>usually not be appropriate to consider such 'trivial' entailments 
>>as useful consequences, since they are not valid rdf- or rdfs- 
>I'm puzzled by the use of "inconsistency" here .. my understanding 
>is that technically, the concept of consistency depends on negation, 
>which is not recognized in RDF.
>[From Metalogic, Geoffrey Hunter:
>"A system S is Simply Consistent iff for no formula A of S are both 
>A and the negation of A theorems of S."  He then goes on to define 
>absolute consistency for systems with the possibility to express 
>negation of any formula.]
>My take on this had been that a D-inconsistent graph is unsatisfiable.
>Ah, I see you're using a different definition of inconsistency 
>So my comment becomes simply:  your definition of inconsistency 
>seems to be, er, "inconsistent" with some other published 

Well, not *inconsistent* with.

My own usage is that 'inconsistent' refers to any unsatisfiable 
syntactic condition, not just those involving negation. 
Description-logic frameworks can become unsatisfiable in other ways 
than having (P and notP ) derivable, since they aren't necessarily 
deductively complete.

But perhaps it would have been better to have used 'unsatisfiable'. 
I'll take that as a last-call fix before final pub, OK?

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Received on Monday, 16 December 2002 12:15:35 UTC

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