Alternation bounds for tree automata

  Kai Salomaa

Abstract:

  We consider alternation depth bounds for tree automata, that is, we limit the number of alternations of existential and universal computation steps. We show that a constant bound guarantees that the forest recognized is regular, whereas already a logarithmic bound enables the automata to recognize a strictly larger class of forests. As a corollary we obtain results on other types of alternation bounds for tree automata. We consider also commutation properties of independent computation steps of an alternating tree automaton.

 Gyenizse Pal 1996. Szeptember 4. Szerda 13:59:27 MET DST