At last Thursday's Semantic Meet-up in Washington DC, a review was given of the
W3C sponsored RDF working meeting that followed the SemTech conference in June. (02)
During the Q&A I asked to what extent was the group pursuing the ideas you put
forth in you BLOGIC keynote at ISWC last fall, which I thought was both
entertaining and well thought out. The answer seemed to be that other than
some discussion of "named graphs", it seems that this W3C group did not want to
look comprehensively into the sorts of issues you had mapped out, and rather,
very much wanted to stay within the existing stack and existing separation of
RDF, SPARQL, Rules, etc. and their definitional underpinnings. (03)
So, here is my question: Are you aware of any groups involved with Common
Logic who are taking up the challenges of BLOGIC (web logic) ? (04)
On Aug 1, 2010, at 1:54 PM, Pat Hayes wrote: (06)
> Just to correct a point of terminology:
> On Jul 29, 2010, at 4:48 PM, Ian Horrocks wrote:
>> OWL and CycL are not really comparable, because OWL is based on a
>> fragment of First Order Logic that is known to be decidable, for
>> which provably correct reasoning algorithms are known and for which
>> effective implementations based on said algorithms are available.
> True, though the CycL reasoning engine also takes advantage of many of
> these decideable cases. (The real difference here is one of academic
> style: the CycL developers are ruthlessly pragmatic and do not care a
> whit for theoretical analyses of completeness or for proving
> correctness.) It should be stated also that proving *correctness* of a
> reasoner is usually fairly easy.
>> OWL's expressive power could, of course, be easily (indeed
>> arbitrarily) extended if one were prepared to compromise on some or
>> all of these design constraints. For example, SWRL extends OWL with
>> Horn clauses (AKA rules), but the resulting language is undecidable,
> True. Strictly, it is semi-decideable.
>> and so only incomplete reasoners are available.
> False. "Complete" means that if a sentence is a theorem, then the
> prover will (eventually) tell you that it is. Complete reasoners (in
> this, textbook, sense) are available for FOL and indeed have been for
> Ian is using "complete" here to mean "complete and decideable", which
> can be characterized as: if a sentence is a theorem, then the prover
> will tell you that - completeness - AND if it isn't a theorem, the
> prover will also tell you that it is not. Full FOL is not decideable
> in this sense. But even when the logic is decideable it can still be
> the case that the complexity of the decision process is arbitrarily
> high, and if you have to terminate it early, you are left in a don't-
> know situation, whether the logic is decideable or not.
>> In fact such reasoners are typically used in a way that is actually
>> incorrect, in that failure to find an entailment is treated as a non-
>> entailment, whereas it should be treated as "don't know".
> I dont think it is fair to say that they are *typically* used in this
> incorrect way. (?)
> Pat Hayes
>> On 29 Jul 2010, at 20:15, Zhuk, Yefim wrote:
>>> Thanks for another great event related to OWL2.
>>> What is your opinion on CycL and CycML (see http://cyc.com)?
>>> From my point of view, this language is more expressive than OWL
>>> and has naturally embedded rules features.
>>> I used this language to describe complex objects and rule-based
>>> business scenarios.
>>> I think, this comes much closer to mimicking real world than OWL
>>> can provide today.
>>> Do you see this one as gaining bigger acceptance and getting to the
>>> level of a standard?
>>> Or maybe there are some limitations that I donít see?
>>> Thank you,
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