Tape-reversal bounded turing machine computations

摘要

This paper studies the classification of recursive sets by the number of tape reversals required for their recognition on a two-tape Turing machine with a one-way input tape.This measure yields a rich hierarchy of tape-reversal limited complexity classes and their properties and ordering are investigated. The most striking difference between this and the previously studied complexity measures lies in the fact that the “speed-up” theorem does not hold for slowly growing tape-reversal complexity classes. These differences are discussed, and several relations between the different complexity measures and languages are established.