It is well-known that the Σk- and Πk-levels of the dot-depth hierarchy and the polynomial hierarchy correspond via leaf languages. We extend this correspondence to the Δk-levels of these hierarchies: . The same methods are used to give evidence against an earlier conjecture of Straubing and Therien about a leaf-language upper bound for BPP.
Bernd Borchert, Klaus-Jörn Lange, F. Stephan
Int. J. Found. Comput. Sci.