On Shrinking Restarting Automata of Window Size One and Two

Abstrakt

Here we study the expressive power of shrinking RWW- and RRWW-automata the window size of which is just one or two. We show that for shrinking RRWW-automata that are nondeterministic, window size one suffices, while for nondeterministic shrinking RWW-automata, we already need window size two to accept all growing context-sensitive languages.

In the deterministic case, shrinking RWW- and RRWW-automata of window size one accept only regular languages, while those of window size two characterize the Church-Rosser languages. In addition, we study shrinking RWW- and RRWW-automata of window size one that are monotone.

Klíčová slova

• Restarting automaton
• Weight function
• Language class
• Window size