On the Length of the Wadge Hierarchy of Omega Context Free Languages
Abstract
We prove in this paper that the length of the Wadge hierarchy of omega context free languages is greater than the Cantor ordinal epsilonomega, which is the omega-th fixed point of the ordinal exponentiation of base omega. The same result holds for the conciliating Wadge hierarchy, defined by J. Duparc, of infinitary context free languages, studied by D. Beauquier. We show also that there exist some omega context free languages which are Sigma0omega-complete Borel sets, improving previous results on omega context free languages and the Borel hierarchy.
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