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Topological Complexity of Context-Free omega-Languages: A Survey (0806.1413v2)
Published 9 Jun 2008 in cs.LO, cs.CC, and math.LO
Abstract: We survey recent results on the topological complexity of context-free omega-languages which form the second level of the Chomsky hierarchy of languages of infinite words. In particular, we consider the Borel hierarchy and the Wadge hierarchy of non-deterministic or deterministic context-free omega-languages. We study also decision problems, the links with the notions of ambiguity and of degrees of ambiguity, and the special case of omega-powers.