The counting hierarchy in binary notation

Abstract

We present a new recursion-theoretic characterization of FCH, the hierarchy of counting functions, in binary notation. Afterwards we introduce a theory of bounded arithmetic, TCA, that can be seen as a reformulation, in the binary setting, of Jan Johannsen and Chris Pollett's system D 0 2 . Using the previous inductive characterization of FCH, we show that a strategy similar to the one applied to D 0 2 can be used in order to characterize FCH as the class of functions provably total in TCA.