Anurag.Acharya@CENTRO.SOAR.CS.CMU.EDU (03/30/88)
AI SEMINAR
TOPIC: Nonmonotonic Temporal Reasoning, and Causation
SPEAKER: Professor Yoav Shoham
Dept. of Computer Science
Stanford University
Stanford, CA 94305
shoham@score.stanford.edu
WHEN: Tuesday, April 12, 1988 3:30pm
WHERE: Wean Hall 5409
ABSTRACT
We define two problems that arise from the conflicting goals of rigor
and efficiency in temporal reasoning, called the {it qualification
problem} and the {it extended prediction problem}, which subsume the
infamous {it frame problem}. We then offer solutions to those.
The solution relies on making nonmonotonic inferences. We present
our very simple, semantical approach to nonmonotonic logics.
We then define a particular nonmonotonic logic, called the logic
of {it chronological ignorance}, which combines
elements of temporal logic and the modal logic of knowledge.
We illustrate how the logic can be used to solve the qualification
problem. (In the unlikely event of time permitting, we will do the same
for the extended prediction problem).
Although the logic of chronological ignorance is, in general, badly
undecidable, we identify a restricted class of theories, called
{it causal theories}, which have very nice properties: They each have
a model that is (in a certain sense) unique, and that is (in a certain sense)
easily computable.
We argue that the above analysis offers an attractive account of
the concept of {it causation}, and of its central role in
common sense reasoning.
The talk presupposes only basic understanding of first-order logic.
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