Open Implication

We argue that the usual trace-based notions of implication and equivalence for linear temporal logics are too strong and should be complemented by the weaker notions of open implication and open equivalence. Although open implication is harder to compute, it can be used to advantage both in model checking and in synthesis. We study the difference between trace-based equivalence and open equivalence and describe an algorithm to compute open implication of Linear Temporal Logic formulas with an asymptotically optimal complexity. We also show how to compute open implication while avoiding Safra’s construction. We have implemented an open-implication solver for Generalized Reactivity(1) specifications. In a case study, we show that open equivalence can be used to justify the use of an alternative specification that allows us to synthesize much smaller systems in far less time.