10/90 A: SFB-Bericht No. 342, pages 1-36 pp.. München: Technische Universiät, Sonderforschungsbereich ``Methoden und Werkzeuge für die Nutzung paralleler Rechnerarchitekturen'', May 1990.
Abstract: For event structures with silent moves the author considers several types of bisimulation that incorperate `true' concurrency to a varying degree, and it is shown how each can be liftet in a uniform way to a congruence w.r.t. action refinement. It is proved that this construction yields the coarsest congruences that respect interleaving, pomset and history preserving bisimulation. In the second part the author introduces an alternative formulation for history preserving bisimulation of safe Petri nets without silent moves: OM-bisimulation is based on ordered markings and allows to decide the corresponding equivalence for finite sets.
Keywords: history preserving bisimulation; safe net; action refinement; event structure; true concurrency.