Great definition. I attended a conference with Stewart Brand last week. He has an interesting new website on Worldchanging.com where the phenomena of CityPlanet is being promoted. He said:
"Without context, there is no meaning."
Thank you for reminding us contextual logic and of John McCarthy and John Sowa's critically important contribution to ontologies that CAN BE APPLIED. The 25th anniversary of REA is approaching. Take a look at:
-------------- Original message --------------
From: Duane Nickull <dnickull@xxxxxxxxx>
> When I say context, I like to use the wordnet definition:
> "discourse that surrounds a language unit and helps to determine its
> Yes - a "river" is always a "river" hence its name. A more accurate
> depiction of what I meant to say is that a certain instance might be a
> "river" in one context and not in another as you suggest.
> See below:
> >> A glass of water sitting on a
> >> desk in front of you will not be elevated in your own tuple stores yet a
> >> glass of water approaching your windshield at 60MPH will based on your
> >> perception that it is a threat to your safety. They are the same object but
t; >> in different contexts have different meaning.
> > Hmm, context as relative speed: I think that is
> > the first time I have come across that particular
> > usage.
> (DUANE): I suspect that the geo-spatial-temporal relationship is one
> context modifier but there would be others. Temperature or granularity
> might be another. For example - what is "solid"? To you and I, a sidewalk
> is solid. To a neutrino, it is not. Not to worry as I don't know of many
> neutrinos who are actively writing ontologies for a human audience but it
> does illustrate the importance of the context being somehow present in an
> I would presume that the example above is based on an intersection of
> multiple contexts. Thinking about how you think is one of the hardest
> activities anyone can do (or so I think).
> >> Even the basic
examples that used to come with Protégé were flawed IMO. The
> >> wine example was screaming for the aspect of context to be included in the
> >> ontology given the concept of "best wine" is contextually dependent upon
> >> your definition and criteria for "best".
> > It is dependent on your concept of "best", yes.
> > Put another way, it uses the term in a very
> > under-determined way. Why do you say this is
> > "contextual", though? What has this situation got
> > to do with contexts, and in what sense of
> > "context"?
> (DUANE): I think the way I interpreted it, it *could* be a contextual
> argument but also might not. Since it is not defined in the example, I
> found the example next to useless.
> What would have been more accurate is a declaration that "
> asserts that is the best wine". T
o me, this more accurately
> reflects the facts that just stating " is the best wine".
> I was aware of the work that had been done but had not realized there were
> active projects. I would like to look into those more. I find the thinking
> very interesting.
> >> Does it mean that I think it is
> >> the best? Is the the author of the ontology?
> > Presumably the latter.
> >> Has some universally accepted
> >> criteria been applied and used to judge it?
> > No.
> >> Without the definition of
> >> "best", the example is largely confusing and meaningless IMO.
> > It does not mean very much, but it is not
> > meaningLESS. It has whatever meaning can be
> > gleaned from the axioms in the ontol
ogy. The same
> > is true for all concept names in any ontology.
> >> There have been some work done around context. Most of it has failed or
> >> resulted in an open ended explosion of hypothesis.
> > Well, quite a lot of reasonably serious work has
> > been done without utter failure, though of course
> > not entirely without controversy. There has been
> > a series of quite technical workshops, for example
> > http://sra.itc.it/events/crr05/,
> > http://www.nexus.uni-stuttgart.de/COMOREA/2006/CallForPapers06_files/comorea06
> > -cfp.pdf
> > and some surveys and overviews are available
> > http://www-poleia.lip6.fr/~brezil/Pages2/Publications/CAI1-99.pdf
> > (now rather old)
> > http://www.cs.bilkent.edu.tr/~akman/book-chapters/mcgraw/mcgraw2002.doc
> > and I belive there is a journal devoted to the
> > topic. John McCarthy was the first to suggest a
> > contextual logic, and it has since been quite
> > sharply formalized by others and has given rise
> > to a lot of work, including many applications and
> > implementations of context-reasoning engines (Try
> > googling "context logic"). Cyc, probably the
> > largest integrated ontology ever built, has been
> > based firmly on context logic for a decade or so,
> > and uses it centrally (their preferred term is
> > 'microtheory' rather than 'context')
> >> It is my hope that one day a serious effort will start to really open this
> >> topic up.
> > Im not sure what you regard as serious, but you
> > might cast an eye over some of the literature. By
> > the way, our logic IKL was developed in
> > provide for a way of handling contexts in full
> > generality but which does not require using a
> > context *logic*. I can expand on this point if
> > you are interested.
> > Pat
> >> Duane
> >> On 2/14/07 9:41 AM, "John F. Sowa" wrote:
> >>> Pat, Chris, Kathy, and Barry,
> >>> The problem of stating necessary and sufficient conditions
> >>> for defining anything is nontrivial, even in mathematics.
> >>> For phenomena in nature or the results of typical human
> >>> behavior, definitive statements are problematical, to say
> >>> the least.
> >>> Belief revision systems, database systems, and kn
> >>> systems distinguish levels of "entrenchment" (whether or not
> >>> they use that term), and I believe that an ontology should also
> >>> make such distinctions at the metalevel. Following are some
> >>> "levels of entrenchment" in descending order of strength:
> >>> 1. Type hierarchy. The classical tree or partial ordering
> >>> introduced by Aristotle and first drawn by (or attributed
> >>> to) Porphyry. It's useful in every field, it's not going
> >>> away, and we should recognize it as the minimal requirement
> >>> for an ontology.
> >>> 2. Necessary distinctions. The differentiae that split any
> >>> type into two or more subtypes. If the split is binary
> >>> (A or not-A), then it is both necessary and sufficient for
>>> distinguishing the two subtypes from one another, but the
> >>> conditions for characterizing the supertype might not be
> >>> necessary and sufficient.
> >>> 3. Constraints. Additional statements that characterize the
> >>> types or the interactions of entities of various types.
> >>> The constraints are necessary relative to the ordinary
> >>> facts in level #4, but they might not be considered
> >>> defining characteristics.
> >>> 4. Ordinary facts. Ground-level assertions that must be
> >>> consistent with statements at the above levels, but they
> >>> may violate defaults at level 5.
> >>> 5. Defaults and probabilities. Statements that are usually
> >>> true of entities of a given type or types, but they are <
BR>> >>> at the bottom of the entrenchment pole. A probable
> >>> statement is a default with an associated value that
> >>> indicates its likelihood or frequency of occurrence,
> >>> given the occurrence of some other condition.
> >>> Systems of entrenchment levels along such lines are widely
> >>> used and should be supported. Cyc, for example, has 3 levels:
> >>> True, true by default, unknown (and the negations -- false
> >>> by default and false). But I think that Lenat would agree
> >>> that a privileged level should be added for some of the
> >>> axioms, especially ones that define the type hierarchy.
> >>> A declaration of which level a particular statement belongs to
> >>> would not be part of the first-order theory, but it would be
;>> a metalevel statement that should definitely be considered
> >>> part of the ontology.
> >>> John
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