Descriptional Complexity of Ambiguity in Symmetric Difference NFAs

We investigate ambiguity for symmetric difference nondeterministic finite automata. we show the existence of unambiguous, finitely ambiguous, polynomially ambiguous and exponentially ambiguous symmetric difference nondeterministic finite automata. we show that, for each of these classes, there is a family of n-state nondeterministic finite automata such that the smallest equivalent deterministic finite automata have o(2^n) states.