Decidability of equivalence for deterministic synchronized tree automata

Abstract

Abstract. Synchronized tree automata allow limited communication between computations in independent subtrees of the input. This enables them to verify, for instance, the equality of two unary subtrees of unlimited size. The class of tree languages recognized by synchronized tree automata is strictly included in the context-free tree languages. As our main result we show that equivalence of tree languages recognized by deterministic synchronized tree automata can be effectively decided. This contrasts the earlier undecidability result for the equivalence problem for nondeterministic synchronized tree automata.