Empty Alternation
نویسندگان
چکیده
We introduce the notion of empty alternation by investigating alternating automata which are restricted to empty their storage except for a logarithmically space-bounded tape before making an alternating transition. In particular, we consider the cases when the depth of alternation is bounded by a constant or a polylogarithmic function. In this way we get new characterizations of the classes AC, SAC and P using a push-down store and new characterizations of the class ΘP2 using Turing tapes.
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