Event Identifier Logic

In this paper we introduce Event Identifier Logic (EIL), which extends Hennessy-Milner logic by the addition of: (1) reverse as well as forward modalities; and (2) identifiers to keep track of events. We show that this logic corresponds to hereditary history-preserving (HH) bisimulation equivalence within a particular true-concurrency model, namely, stable configuration structures. We also show how natural sublogics of EIL correspond to coarser equivalences. In particular, we provide logical characterisations of weak-history- preserving (WH) and history-preserving (H) bisimulation. Logics corresponding to HH and H bisimulation have been given previously, but none, as far as we are aware, corresponding to WH bisimulation (when autoconcurrency is allowed). We also present characteristic formulas that characterise individual structures with respect to history-preserving equivalences.