BIB-VERSION:: CS-TR-v2.0
          ID:: STAN//CS-TR-94-1501
       ENTRY:: February 28, 1994
ORGANIZATION:: Stanford University, Department of Comuputer Science
       TITLE:: Deriving Properties of Belief Update from Theories of Action
        TYPE:: Technical Report
      AUTHOR:: Val, Alvaro del
      AUTHOR:: Shoham, Yoav
        DATE:: February 1994
       PAGES:: 48
    ABSTRACT:: We present an approach to database update as a form of non
               monotonic temporal reasoning, the main idea of which is the
               (circumscriptive) minimization of changes with respect to a
               set of facts declared ``persistent by default.'' The focus of
               the paper is on the relation between this approach and the
               update semantics recently proposed by Katsuno and Mendelzon.
               Our contribution in this regard is twofold:
 
               - We prove a representation theorem for KM semantics in terms
               of a restricted subfamily of the operators defined by our
               construction.
 
               - We show how the KM semantics can be generalized by relaxing
               our construction in a number of ways, each justified in
               certain intuitive circumstances and each corresponding to one
               specific postulate. It follows that there are reasonable
               update operators outside the KM family.
 
               Our approach is not dependent for its plausibility on this
               connection with KM semantics. Rather, it provides a
               relatively rich and flexible framework in which the frame and
               ramification problems can be solved in a systematic way by
               reasoning about default persistence of facts.
       NOTES:: [Adminitrivia V1/Prg/19940228]
         END:: STAN//CS-TR-94-1501