A Note on Probabilistic Rebound Automata

摘要

This paper introduces a probabilistic rebound au- tomaton (pra), and investigates its accepting power and closure property. We show that (1) the class of languages recognized by pra's with error probability less than 1/2, PRA, is incomparable with the class of context-free languages, (2) there is a language accepted by a two-way nondeterministic one counter automa- ton, but not in PRA, and (3) there is a language accepted by a deterministic one-marker rebound automaton, but not in PRA. We also show that PRA is not closed under concatenation and Kleene +.