D. McDermott and J. Doyle, Non-Monotonic Logic I. Artificial Intelligence, 13 (1\&2), 1980.

Author of the summary: J. William Murdock, 1997, murdock@cc.gatech.edu

Cite this paper for:

• Dynamic systems of information can be modeled using a level of mathematical rigor comparable to that provided to static systems by predicate calculus.

Keywords: Non-Monotonic Logic

Systems: TMS (Truth Maintenance System)

Summary: Introduces the notion of non-monotonic logic, a logical
system in which new information may be added to invalidate old
conclusions.  Motivates this concept by observing the necessity of
revising incomplete world models in real life situations.  Introduces
a new operator {\sf M} which denotes that a proposition is consistent
with the current knowledge base.  Discusses a variety of approaches to
processing consistency.  Defines a broad array of terms relating to
non-monotonic logic, concentrating on the notion of a ``fixed point''
which is an extension of a notion from monotonic logic.  Uses these
terms to prove some theorems.  Establishes a proof procedure (i.e. a
processing account) based on the development of internally coherent
"tableaus" (i.e. truth table entries).  Briefly introduces TMS and
related programs as a rough implementation of these ideas.  Raises
some open technical questions.

Summary author's notes:

• This summary came from a file which had the following disclaimer: "The following summaries are the completely unedited and often hastily composed interpretations of a single individual without any sort of systematic or considered review. As such it is very likely that at least some of the following text is incomplete, inadequate, misleading, or simply wrong. One might view this as a very preliminary draft of a survey paper that will probably never be completed. The author disclaims all responsibility for the accuracy or use of this document; this is not an official publication of the Georgia Institute of Technology or the College of Computing thereof, and the opinions expressed here may not even fully match the fully considered opinions of the author much less the general opinions of the aformentioned organizations."