Beyond Vacuity: Towards the Strongest Passing Formula
Hana Chockler, Arie Gurfinkel, Ofer Strichman · 2008
Given an LTL formula phi in negation normal form, it can be strengthened by replacing some of its literals with FALSE. Given such a formula and a model M that satisfies it, vacuity and mutual vacuity attempt to find one or a maximal set of literals, respectively, with which phi can be strengthened while still being satisfied by M. We study the problem of finding the strongest LTL formula that satisfies M and is in the Boolean closure of strengthened versions of phi as defined above. This formula is stronger or equally strong to any formula that can be obtained by vacuity and mutual vacuity. We present our algorithms in the framework of lattice automata.