Maximal Models of Assertion Graph in GSTE

Abstract. Generalized symbolic trajectory evaluation (GSTE) is an extension of symbolic trajectory evaluation (STE). In GSTE, assertion graphs are used to specify properties in a special form of regular automata with antecedent and consequent pairs. This paper presents a new model characterization, called maximal models, for an assertion graph with important properties. Besides their own theoretical significance, maximal models are used to show the implication of two assertion graphs in GSTE. We show that, contrary to the general belief, an assertion graph may have more than one maximal model. We present a provable algorithm to find all maximal models of a linear assertion graph. We devise an algorithm for finding a maximal model for an arbitrary assertion graph.