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Re: [ontolog-forum] Scheduling a Discussion [was: CL, CG, IKL and the re

To: "Adrian Walker" <adriandwalker@xxxxxxxxx>
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Wed, 2 Jan 2008 19:02:02 -0800
Message-id: <p0623091ac3a1ff867fdf@[]>
>Hi Pat --
>You wrote....
>At least four distinct logics for context have 
>been fully developed and at least two of them 
>are now deployed in industrial-scale working 
>software systems.
>Most interesting.  Do you have references that 
>describe what the deployed ones are doing 
>industrially please?    (01)

Well, Cyc uses a context logic, as does, I 
believe, Ontoworks. Cyc has many real-world 
applications (check their website for details) 
and Ontoworks stuff is being used heavily by 
several government agencies. I don't have 
academic references as this stuff is all highly 
proprietary.    (02)

Pat    (03)

>Thanks!                 -- Adrian
>Internet Business Logic
>A Wiki and SOA Endpoint for Executable Open Vocabulary English
>Online at 
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>Adrian Walker
>On 1/2/08, Pat Hayes <<mailto:phayes@xxxxxxx>phayes@xxxxxxx> wrote:
>  >  > [DN]  Would make an interesting ontolog session sometimes in 2008.
>>>  Maybe Peter can schedule a call.
>>[ppy] Sure, I'd be most happy to. I'd need a more refined statement of
>>WHAT (exactly) it is, that folks would like to discuss, and WHO are
>>the people they would like to hear from (or hear discussing the issue
>>at hand).
>>Are we going for CL, CG, IKL and the relationship between symbols in
>>the logical "universe of discourse" and individuals in the "real
>>world"? Representing Context in general? How CL/IKL deals with
>>context? ...
>>I solicit input from those interested on:
>>(a) A clear statement of the "topic",
>FWIW, this is not a new topic. The general idea of the relevance of
>context in language and KR and logic has been discussed now for
>several decades, including at least one entire series of successful
>interdisciplinary research meetings entirely devoted to it. At one of
>the very first 'ontology summit' meetings (at Heidelburg in, if my
>memory serves me right, 1997), a whole session was devoted to an
>attempt to define and clarify the notion. At least four distinct
>logics for context have been fully developed and at least two of them
>are now deployed in industrial-scale working software systems. So we
>are not, or at least SHOULD not be, working in an entirely new area
>Unless all the participants are at least marginally aware of all this
>preceding effort and the general shape of the debates that have gone
>on, we will only be repeating history.
>FWIW, here is the definition of "context" that I put forward at
>Heidelberg, and which seemed to meet with some general acceptance.
>Theories of meaning invariably focus their attention on some subset
>of the many factors which can possibly influence the actual meaning
>conveyed by a meaningful utterance or sentence or diagram, or any
>symbolic structure or act. The other factors or aspects which may
>influence meaning, but which are not explicitly examined by the
>theory, are often referred to as "context". Thus, the term "context"
>has no single meaning: it is used simply to refer to anything (or
>sometimes everything) which can influence meaning but which is
>outside the scope of the current theory. It is always defined
>This means, in turn, that there is no such 'thing' as an objective
>context, and so there is no general theory of contexts, or science of
>contexts, which can be applied to all cases of "context". Indeed,
>since, in the limit, it seems that almost anything can influence
>meaning under some circumstances, it follows that anything at all can
>be considered to be a context. One sees evidence for this conclusion
>by examining the proceedings of any of the 'context workshops', and
>checking carefully what each author means by the word "context". At
>the second such workshop (held at MIT in 2003), every single
>contributing author had a different notion, ranging in scope from a
>single occurrence of a single word in a single sentence (as exhibited
>in so-called 'priming' experiments) to an entire social/cultural
>milieu, such as China in the 13th century.
>Which, to get back to the topic, is why starting a discussion of
>contexts with any attempt to "define the topic" is unlikely to
>succeed, for the very good reason that there really is no such topic.
>(And even if by some miracle it does, that success will only be
>temporary, because you can guarantee that someone else out there will
>BTW, partly as a reaction to this observation, the formalized
>'context logics' developed by McCarthy, Guha (and John Sowa, though
>he used a different terminology) are deliberately agnostic as to the
>nature of "contexts", and adopt a theoretical stance along the lines
>of: a context is whatever satisfies the axioms of my logic/theory of
>contexts (analogous to a mathematical reply to a question such as
>'what is a commutative algebra?'). However, the apparent
>reasonableness of this 'mathematical' stance is somewhat undermined
>by the fact that none of the extant such logics provide more than one
>or two axioms or principles, and the very few that they have provided
>have obvious, immediate counterexamples in cases that everyone agrees
>should be possible to treat as contexts (such as a time-interval).
>This situation has not changed in about a decade of intensive work on
>these logics, which to my mind at least reduces the 'mathematical
>theory' position to absurdity: apparently, there is no mathematical
>theory of contexts. And calling a diverse collection of things by a
>single name is not good science, nor good engineering, nor good
>methodology. For example, a good deal of the work on "context logic"
>has been a slow rediscovery of ideas that were already well known and
>thoroughly investigated in temporal logic, but because it was seen as
>being about "contexts" instead of mere time-intervals, the earlier
>work (which in many cases was vastly superior, having been done by
>some of the best philosophical logicians of the last century) was
>The more popular recent stance is that there are many kinds of
>context, each with its own axioms and principles: time-intervals,
>time-points, sets of beliefs, linguistic conventions, conversational
>settings, etc.. Well, OK: but all of these (and others) already had
>more or less mature fields investigating them, without using the
>"context" word. So now the question arises, what value is gained by
>using a single term to refer to them all? It suggests a commonality
>which does not appear to be present. Time-intervals and states of
>belief, in particular - the two most commonly suggested "kinds" of
>context - seem to have almost nothing in common at all. If anyone can
>suggest a single axiom which relates propositions or sentences to
>contexts, and is true both when this means the proposition is true at
>or in that time, and also when it means the proposition is entailed
>by a set of beliefs, I would be delighted to be shown it. I have made
>this challenge repeatedly to proponents of 'contexts' for many years,
>and have yet to be given an answer.
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