On Parallel Communicating Grammar Systems and Correctness Preserving Restarting Automata

Abstract. This paper contributes to the study of Freely Rewriting Restarting Automata (FRR-automata) and Parallel Communicating Grammar Systems (PCGS), which both are useful models in computational linguistics. For PCGS we study two complexity measures called generation complexity and distribution complexity, and we prove that a PCGS Π , for which the generation complexity and the distribution complexity are both bounded by constants, can be transformed into a freely rewriting restarting automaton of a very restricted form. From this characterization it follows that the language L(Π) is semi-linear, that its characteristic analysis is of polynomial size, and that this analysis can be computed in polynomial time.