On the complexity of 2-monotone restarting automata

Abstract

The R-automaton is the weakest form of the restarting automaton. It is shown that the class of languages accepted by these automata is incomparable under set inclusion to the class of growing context-sensitive languages. In fact, this already holds for the class of languages that are accepted by 2-monotone R-automata. Further it is shown that already this class contains NP-complete languages. Thus, already the 2-monotone R-automaton has a surprisingly large expressive power. © Springer-Verlag Berlin Heidelberg 2004.