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C00002 00002	John	McCarthy has continued his work on epistemological problems
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John	McCarthy has continued his work on epistemological problems
of artificial intelligence, especially non-monotonic reasoning
and the representation of knowledge and belief in first order logic.
[McCarthy 1980] summarizes the state of the work on non-monotonic
reasoning as of Winter 1980, and [McCarthy 1979] summarizes the 1979
results on representation of concepts and propositions.

%3McCarthy, John (1979)%1: 
"First Order Theories of Individual Concepts and Propositions", 
in Michie, Donald (ed.) %2Machine Intelligence 9%1, (University of
Edinburgh Press, Edinburgh).
.<<aim 325,concep[e76,jmc]>>

%3McCarthy, John (1980)%1: 
"Circumscription - A Form of Non-Monotonic Reasoning", %2Artificial
Intelligence%1, Volume 13, Numbers 1,2, April.
.<<aim 334, circum.new[s79,jmc]>>

	Beyond these results, McCarthy has developed a more general
form of circumscription suitable for automatically generating frame
axioms.

	He has also continued his work on the Elephant formalism
for representing programs.  This permits entirely conventional
programs to be regarded as sentences of logic from which their
properties follow without any special logic of programming.
This involves representing variables including the program counter
explicitly as functions of time and has led to controversy with
the advocates of temporal logic.  Elephant also allows explicit
reference to past events and actions without having to declare
variables or arrays to represent the information that has to
be remembered by the program.  This makes it a higher level language
than almost all present languages, but it is not yet clear how
to take best advantage of this fact.  Results on Elephant will
be published shortly.