On the Length of the Wadge Hierarchy of ω-Context Free Languages
We prove in this paper that the length of the Wadge hierarchy of ω-context-free languages is greater than the Cantor ordinal eω, which is the ωth fixed point of the ordinal exponentiation of base ω. We show also that there exist some Σω0-complete ω-context-free languages, improving previous results on ω-context-free languages and the Borel hierarchy.