3 LOGICS FOR BRANCHING BISIMULATION

Three temporal logics are introduced that induce on labeled transition systems the same identifications as branching bisimulation, a behavioral equivalence that aims at ignoring invisible transitions while preserving the branching structure of systems. The first logic is an extension of Hennessy-Milner Logic with an ''until'' operator. The second one is another extension of Hennessy-Milner Logic, which exploits the power of backward modalities. The third logic is CTL* without the next-time operator. A relevant side-effect of the last characterization is that it sets a bridge between the state- and action-based approaches to the semantics of concurrent systems.