Virtual Worldwide Seminar Project
AI Notions of Context
John McCarthy1 |
December 9, 1998 |
Abstract
There will be overlap with my 1993 IJCAI article,
http://www-formal.stanford.edu/jmc/context.html, but I'll emphasize
new stuff.
We treat contexts as objects in (mostly) first order theories. The
most basic relation is _Ist(c,p)_ asserting that the proposition _p_
is true in the context _c_. Every assertion, including those about
contexts is made in a context, and therefore when we assert
_Ist(c,p)_, we do it in some context _c0_ and therefore write
c0: ist(c,p).
Besides propositions, there are individual concepts, and
_Value(c,exp)_ denotes the value that the individual concept _exp_ has
in the context _c_.
We consider relations among contexts such as that one context
specializes another or has a certain relation to that of another.
Here are some ideas and topics that will be discussed.
- "What is context?" is a misleading question to be replaced by "What
kinds of context objects are useful in AI, philosophy and
linguistics?" There are many.
- All assertions about particular contexts are made in contexts.
There is no outermost context, and the outermost considered so far may
be _transcended_.
- Two contexts with the same true sentences may differ in their
relation to other contexts.
- contexts associated with the beliefs of a person
- contexts associated with the contents of a database
- contexts associated with particular times and places, e.g. this
abstract or the context associated with the actual lecture
- relations between the values of expressions in two different
contexts asserted in a third, outer, context, e.g.
c[this abstract]: Value(c[Stanford-Stockholm seminar of 1998 January
16],Lecturer)
=
Value(c[Stanford Computer Science Department],John McCarthy).
- contexts associated with assumptions including counterfactuals,
e.g.
c[if another car had come over the hill when you passed that Lexus]
- contexts associated with mathematical theories, e.g. group theory
or common sense theories about the different kinds of automobiles
- fictional contexts, e.g. that of the Sherlock Holmes stories
The problem for AI is to get theories expressed in languages of
mathematical logic within which computer programs can reason about the
relations between objects associated with different contexts.
Slides
Are UP! title.html
(Wed Dec 9 03:59:03 1998)
Gzipped, tarred version (so can look at locally)
jmc.tar.gz
Attendees
- Formal Reasoning Group (Stanford University, USA)
- Mechanized Reasoning Group (DISA, Trento, Italy)
- Paolo Bouquet,
Roger Young, and their colleagues at University of Dundee (Scotland, U.K.)
- Erik
Sandewall (Linköping university, Sweden)
- Luca
Spalazzi (University of
Ancona, Italy)
- John Barnden (School of Computer Science, University of Birmingham, U.K.)
1 John McCarthy
Room 208, Gates Building 2A [click on the building for directions]
Computer Science Department
Stanford University
Stanford, California 94305-9020
U.S.A.
jmc@cs.stanford.edu
http://www-formal.stanford.edu/jmc
|