Agreed. I hear enough of this crap elsewhere, let's focus on ontology. (01)
-Chris (02)
Nicola Guarino wrote:
> Folks,
>
> these discussions are very nice, but I don't think they are directly
> related to the main focus of this list, i.e. the Ontology Summit 2007,
> which is supposed to concentrate on the question "what is an ontology".
>
> I am already having a VERY hard time following the ontology summit
> discussion, and these recent messages don't really help to keep the
> discussion focused.
>
> I am afraid I have just to give up any kind of active presence if the
> discussion on this list goes out of its main focus.
>
> Best,
>
> Nicola
>
> On 5 Mar 2007, at 22:31, John F. Sowa wrote:
>
>> Leo,
>>
>> To continue my point that efficiency *always* depends
>> on what you're trying to do, I would like to address the
>> problem of finding a consistent set of constraints:
>>
>>> I, as usual, recommend the
>>> description logic complexity navigator:
>>> http://www.cs.man.ac.uk/~ezolin/logic/complexity.html
>>
>> Given a set of arbitrary first-order constraints, the problem
>> of proving consistency is NP complete. Yet every SQL database
>> permits arbitrary first-order constraints.
>>
>> Q: How is possible to prove that the constraints are consistent?
>>
>> A: Trivially.
>>
>> The point is that no database designer *ever* begins with
>> an arbitrary set of constraints. They *always* begin with
>> some actual data -- a sample DB that shows what kind of data
>> they expect to work with.
>>
>> That sample DB consists of a set of entities and a set of
>> relations that are assumed to be true of those entities.
>> In other words, the starting point is a Tarski-style model.
>>
>> Although *finding* a model is NP complete, the task of
>> *checking* constraints is trivial, if a model is given.
>>
>> Given a proposed set of first-order constraints that do not
>> depend on any recursive definitions -- i.e., anything expressible
>> in SQL WHERE clauses -- the evaluation time in terms of a sample
>> model takes, in the worst case -- polynomial time.
>>
>> If all the constraints turn out to be true of the model, then
>> they are consistent. If any of them turn out to be false,
>> either throw them away or revise them to make them true.
>>
>> Bottom line: If you're trying to define axioms or definitions
>> for an ontology, a database, or a knowledge base, it's a good
>> idea to start with at least one illustrative example.
>>
>> John
>>
>>
>> _________________________________________________________________
>> Msg Archives: http://ontolog.cim3.net/forum/ontology-summit/
>> Subscribe/Config:
>> http://ontolog.cim3.net/mailman/listinfo/ontology-summit/
>> Unsubscribe: mailto:ontology-summit-leave@xxxxxxxxxxxxxxxx
>> Community Files: http://ontolog.cim3.net/file/work/OntologySummit2007/
>> Community Wiki: http://ontolog.cim3.net/cgi-bin/wiki.pl?OntologySummit2007
>> Community Portal: http://ontolog.cim3.net/
>>
>
>
>
>
> -----------------------------------------------------------------------------
>
> Nicola Guarino
>
> Editor in Chief, Applied Ontology (IOS Press)
>
> Head, Laboratory for Applied Ontology (LOA), ISTC-CNR
>
> Institute for Cognitive Sciences and Technologies
>
> National Research Council
>
>
> mobile: +39 333 5865383
>
> email: guarino@xxxxxxxxxx <mailto:guarino@xxxxxxxxxx>
>
> web site: http://www.loa-cnr.it
>
>
>
>
> ------------------------------------------------------------------------
>
>
> _________________________________________________________________
> Msg Archives: http://ontolog.cim3.net/forum/ontology-summit/
> Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontology-summit/
> Unsubscribe: mailto:ontology-summit-leave@xxxxxxxxxxxxxxxx
> Community Files: http://ontolog.cim3.net/file/work/OntologySummit2007/
> Community Wiki: http://ontolog.cim3.net/cgi-bin/wiki.pl?OntologySummit2007
> Community Portal: http://ontolog.cim3.net/ (03)
--
Dr. Christopher A. Welty IBM Watson Research Center
+1.914.784.7055 19 Skyline Dr.
cawelty@xxxxxxxxx Hawthorne, NY 10532
http://www.research.ibm.com/people/w/welty (04)
_________________________________________________________________
Msg Archives: http://ontolog.cim3.net/forum/ontology-summit/
Subscribe/Config: http://ontolog.cim3.net/mailman/listinfo/ontology-summit/
Unsubscribe: mailto:ontology-summit-leave@xxxxxxxxxxxxxxxx
Community Files: http://ontolog.cim3.net/file/work/OntologySummit2007/
Community Wiki: http://ontolog.cim3.net/cgi-bin/wiki.pl?OntologySummit2007
Community Portal: http://ontolog.cim3.net/ (05)
|