On the Structure of Log-Space Probabilistic Complexity Classes (Extended Abstract)
نویسنده
چکیده
We investigate hierarchical properties and log-space reductions of languages recognized by log-space probabilistic Turing machines, Arthur-Merlin games and Games against Nature with log-space probabilistic veriiers. For each log-space complexity class, we decompose it into a hierarchy based on corresponding multihead two-way nite automata and we (eventually) prove the separation of the hierarchy levels (even over one letter alphabet); furthermore, we show log-space reductions of each log-space complexity class to low levels of its corresponding hierarchy. We nd probabilistic (and \probabilistic+nondeterministic") variants of Savitch's maze threading problem which are log-space complete for PL (and respectively P) and can be recognized by two-head one-way and one-way one-counter nite automata with probabilistic (probabilistic and nondeterministic) states.
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