Deciding Equivalence of Finite Tree Automata

Helmut Seidl
1990 SIAM journal on computing (Print)  
We s h o w : f o r mJe~j constant m i t can be decided i n p o l y n o m i a l time w h e t h e r or not two m-ambiguous finite tree automata are equivalent. In general, inequivalence for finite tree automata is DEXPTIfdE-complete v).r.t, logspace reductions, and PSPACE-complete w.r.t, logspace reductions, i f the automata in question are supposed to accept only finite languages. For finite tree automata u i t h coefficients in a field R we give a polynomial time algorithm for deciding
more » ... -equivalence provided R-operations and R-tests for 0 can be perfor-,ned i n constant time. We apply this algorithm for deciding ambiguityinequivalence 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.
doi:10.1137/0219027 fatcat:pfsympzzy5anbi2hkmddi6kpu4