Effective decomposability of sequential behaviours

Abstract

A process is prime if it cannot be equivalently expressed as a parallel composition of nonempty processes. We characterize all non-prime normed BPA processes together with their prime decompositions by means of normal forms which are designed in this paper. Using this result we demonstrate decidability of the problem whether a given normed BPA process is prime; moreover, we show that non-prime normed BPA processes can be decomposed into primes effectively. Finally, we prove that bisimilarity is decidable in a natural subclass of normed PA processes.