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C00002 00002	circum.mor[f82,jmc]	More on circumscription - for IJCAI or AAAI
C00004 00003	Introduction
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circum.mor[f82,jmc]	More on circumscription - for IJCAI or AAAI

Abstract: Circumscription is a method of non-monotonic reasoning
introduced in (McCarthy 1980).  The present paper contains a
generalized notion of circumscription, the notion of circumscription
with priorities which seems to be required by some applications,
interpretations of circumscription as communication and database
conventions and as a rule of inference, and the mathematical notion
of circumscriptive theory.  Also the circumscription formula is now
second order rather than a schema of first order formulas.
  The paper is self-contained,
but most of the motivation presented in (McCarthy 1980) is not
repeated.
Introduction

	The object of circumscription is to formalize
and computerize the slogan of Ockham's razor:
"Entities shall not be multiplied beyond necessity".
The entities in question are the elements  x  of a domain  X  that
satisfy a formula  E[x],  and necessity is expressed by an axiom  A[P],
imposing a condition on a predicate  P.