This paper shows that many simulation equivalences over processes can be characterised by a single parameterised modal logic formula. For many equivalences there is a parameterised modal logic formula f(t) such that for every pair of processes P and Q, P Q if and only if P j= f(Q). For any speci c P the formula f(P ) becomes a x point formula of the normal modal logic K . Strong bisimulation eq...

A domain theoretical denotational model is given for a simple sublanguage of CCS extended with divergence operator. The model is derived as an abstraction on a suitable notion of normal forms for labelled transition systems. It is shown to be fully abstract with respect to observational precongruence.

In this paper we extend a performance measure sensitive Markovian bisimulation congruence based on yield and bonus rewards that has been previously defined in the literature, in order to aggregate more states and transitions while preserving compositionality and the values of the performance measures. The extension is twofold. First, we show how to define a performance measure sensitive Markovi...

.Mmtract. In thL~ paper the first infinite series of translation nets with nonabelian translation groups and a large number of parallel classes are constructed. For that purpose we investigate partial congruence partitions (PCPs) with at least one normal component. Two series correspond to partial congruence partitions containing one normal elementary abelian component. The construction results...

A subgroup of V containing a principal congruence subgroup T(«) is said to be a congruence subgroup, and is of level « if « is the least such integer. In a recent article [2] the writer determined all normal subgroups of T of genus 1 (see [l] for the definition of the genus of a subgroup of r). An interesting question that arises is to decide which of these are also congruence subgroups. In thi...