Model repair via SAT solving -

Abstract

We consider the following model repair problem: given a finite Kripke structure M and a specification formula η in some modal or temporal logic, determine if M contains a sub-structure Ḿ that satisfies η. That is, can M be repaired to satisfy the specification η by deleting some transitions? We map an instance (M, η) of model repair to a Boolean formula repair (M, η) such that (M, η) has a solution iff repair (M, η) is satisfiable. Furthermore, a satisfying assignment determines which transitions must be removed from M to generate a model Ḿ of η. Thus, we can use any SAT solver to repair Kripke structures. Furthermore, using a complete SAT solver yields a complete algorithm: it always finds a repair if one exists. We augment the basic method by adding state-space reduction methods, and also a method to repair hierarchical Kripke strucutres.