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RE: [ontac-forum] Ontology change 'on the fly' - does the upperontology

To: "ONTAC-WG General Discussion" <ontac-forum@xxxxxxxxxxxxxx>
From: "West, Matthew R SIPC-DFD/321" <matthew.west@xxxxxxxxx>
Date: Fri, 19 May 2006 16:38:16 +0100
Message-id: <A94B3B171A49A4448F0CEEB458AA661F032BBD90@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Dear Pat,
I'm afraid this is not true:
> *** But, BUT, BUT!!!!! ***
> If any two ontology-driven systems want to work together, that upper ontology, WHATEVER IT IS, has to be the same.
If you don't have a common upper ontology you do need to have a mapping between the upper ontologies you do have. What is true that having a common upper ontology give efficiency benefits as the number of ontologies you are trying to integrate rises. At about 4 ontologies a common ontology (at all levels that are shared) pays off.
-----Original Message-----
From: ontac-forum-bounces@xxxxxxxxxxxxxx [mailto:ontac-forum-bounces@xxxxxxxxxxxxxx]On Behalf Of Cassidy, Patrick J.
Sent: 19 May 2006 14:50
To: ONTAC-WG General Discussion
Subject: RE: [ontac-forum] Ontology change 'on the fly' - does the upperontology realy matter?

Re: the question - does the upper ontology matter much?
My recollection from talking to Doug Lenat is that when he says that the upper ontology is not the most important part -
he means that several different upper ontologies might serve equally well, and there is no requirement for one specific upper ontology.
*** But, BUT, BUT!!!!! ***
If any two ontology-driven systems want to work together, that upper ontology, WHATEVER IT IS, has to be the same.
I think Cathy's example of 'person' is a good illustration of why.  If a system decides to change its upper ontology on the fly, it should be prepared for serious chaos.
So let us not confuse the issue by failing to recognize the distinction between one group choosing an upper ontology (or no upper ontology) for its own isolated purposes, and multiple groups choosing an upper ontology for communication between semantic systems.  These are very different application scenarios, having different requirements.  The upper ontology has an additional function in providing the "common sense" implicit knowledge that people need to fall back on more general principles when the specialized knowledge and pre-existing experience are insufficient to solve a problem -- but the ONTACWG deliberations have not reached the implementation level where that function is of direct concern.
Since the ONTACWG is focused mainly on semantic interoperability, the questions of whether different upper ontologies can function together **in an interoperability scenario** should not be ignored or conflated with a system operating independently to solve some problem.
The AI community discovered a long time ago that most of the reasoning people do about practical problems depends heavily on specialized knowledge of the domain of interest.  That has been confirmed many times, and a recent example would be the Halo project.   But these domain-specific pilots invariably involve systems operating independently, not systems trying to **interoperate** semantically.  In our discussions I hope we can keep these very important distinctions right at the forefront, since if they are ignored it will lead to unnecessary confusion about the role of the upper ontology.

Patrick Cassidy
MITRE Corporation
260 Industrial Way
Eatontown, NJ 07724
Mail Stop: MNJE
Phone: 732-578-6340
Cell: 908-565-4053
Fax: 732-578-6012
Email: pcassidy@xxxxxxxxx


From: ontac-forum-bounces@xxxxxxxxxxxxxx [mailto:ontac-forum-bounces@xxxxxxxxxxxxxx] On Behalf Of Catherine Legg
Sent: Friday, May 19, 2006 2:44 AM
To: ontac-forum@xxxxxxxxxxxxxx
Subject: [ontac-forum] Ontology change 'on the fly'

First of all, apologies to all for the unfortunate header on my previous message – I’m a bit out of practice posting to lists like these, and I’m receiving this list in digest form (which actually I’m finding a bit confusing, I might change that).


Thanks, Chris, for the reminder about CL, with which I’m familiar. Following Leo – yes, what was concerning me was issues of inference engine design qua changeable arities. It just sounded to me like a recipe for chaos (just imagining the kind of backchaining that might result….!!!) The suggestion was made that Bundy was envisaging a system involving a metalevel of reasoning whereby changes to the formalism itself would be applied at that level following some independent set of heuristics. I wouldn’t want to rule that out in principle but would love to hear some actual details of rules which might be applied at that level.


There was a post by Barry Smith which I would’ve liked to read but it got scrubbed in my digest due (I think) to being in HTML – I don’t suppose it could be re-posted?


John I was interested to read your description of your evolution away from advocating axiom-rich ontologising towards recommending something much closer to Wordnet, indeed a system where (if I have it right) the only assertions in the ontology are purely definitional, concerning the meanings of terms, and no empirical claims are made. This sounds prima facie plausible. However, can a sharp distinction be made between these two categories of claim? I don’t think so. I think that is one of the lessons of Peirce’s pragmatism. Consider for instance, “Electrons have a negative charge”. This was an empirical claim at some early stage of atomic theory yet is now analytically true. “Cats have whiskers” – empirical or definitional?


Also, when you say that assertions in any upper ontology are “much less important” than assertions in lower-middle and domain ontologies I think that this statement equivocates dangerously on 2 different meanings of “Much less important”:

i) Much fewer ontologist working hours are spent on this part of the ontology (true)

ii)  Removing or changing these assertions breaks or changes less (false!!)


I can remember quite a few times when I was working at Cycorp that relatively minor changes made at the upper level had (rather fascinatingly) unintended consequences for folks working on specific projects. (To give just one example, ‘person’ (the legal – social entity) was separated out from ‘human being’ (the species) and various inferences which depended on those two concepts being munged together then broke….)







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