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From: mklein@AISUNG.CS.UIUC.EDU (Mark Klein)
Newsgroups: mod.ai
Subject: Nonmonotonic Reasoning
Message-ID: <8611041530.AA05646@aisung.cs.uiuc.edu.cs.uiuc.edu>
Date: Tue, 4-Nov-86 10:30:29 EST
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Posted: Tue Nov  4 10:30:29 1986
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My understanding of nonmonotonic reasoning (NMR) is different from what you
described in a recent ailist posting. As I understand it, NMR differs
from monotonic reasoning in that the size of the set of true theorems
can DECREASE when you add new axioms - thus the set size does not
increase monotonically as axioms are added. It is often implemented
using truth maintenance systems (TMS) that allow something to be justified
by something else NOT being believed. Monotonic reasoning, by contrast,
could be implemented by a TMS that only allows something to be justified by
something else being believed. Default reasoning is an instance of
nonmonotonic reasoning. Nonmonotonic reasoning is thus not synonymous with
truth maintenance.

			Mark Klein