Abstract. A prototype assistant, NL2ACTL, is presented for the formalization ofbehavioural requirements for the design of reactive systems. NL2ACTL is a tool for the automatic translation of Natural Language sentences, into formulae of the action-based temporal logic ACTL. The Natural Language sentences are used to express informal requirements of reactive systems. ACTL is suitable for expressing properties of reactive systems, specified by means of process algebra terms. NL2ACTL was realized using a general development environment for Natural Language Processing and it has been interfaced with a verification environment which allows behavioural and logical properties of reactive systems to be checked.

A system is described which supports proofs of both behavioural and logical properties of concurrent systems; these are specified by means of a process algebra and its associated logics. The logic is an action based version of the branching time logic CTL which we call ACTL; it is interpreted over transition labelled structures while CTL is interpreted over state labelled ones. The core of the system are two existing tools, AUTO and EMC. The f'wst builds the labelled transition system corresponding to a term of a process algebra and permits proof of equivalence and simplification of terms, while the second chocks validity of CTL logical formulae. The integration is realized by memos of two translation functions from the action based branching time logic ACTL to CTL and from transition-labelled to state-labelled structures. The correctness of the integration is guaranteed by the proof that the two functions when coupled preserve satisfiability of logical formulae.

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A verification environment for the T-calculus is presented. The environment takes a direct advantage of a general theory which allows to associate ordinary finite state automata to a wide class of ucalculus agents, so that equivalent automata are associated to equivalent ~-calculus agents. A key feature of the approach is the reuse of efficient algorithms and verification techniques which have been developed and implemented for ordinary automata.