Abstract
We show: for every constant m it can be decided in polynomial time whether or not two m-ambiguous finite tree automata are equivalent. In general, inequivalence for finite tree automata is DEXPTIME-complete w.r.t. logspace reductions, and PSPACE-complete w.r.t. logspace reductions, if the automata in question are supposed to accept only finite languages. For finite tree automata with coefficients in a field R we give a polynomial time algorithm for deciding ambiguity-equivalence provided R-operations and R-tests for 0 can be performed in constant time. We apply this algorithm for deciding ambiguity-inequivalence of finite tree automata in randomized polynomial time.
Furthermore, for every constant m we show that it can be decided in polynomial time whether or not a given finite tree automaton is m-ambiguous.
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© 1989 Springer-Verlag Berlin Heidelberg
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Seidl, H. (1989). Deciding equivalence of finite tree automata. In: Monien, B., Cori, R. (eds) STACS 89. STACS 1989. Lecture Notes in Computer Science, vol 349. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0029009
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DOI: https://doi.org/10.1007/BFb0029009
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