A speed-up theorem without tape compression

AbstractWe shall show that, for each nondeterministic single-tape Turing machine M of time complexity T(n)⩾n2 and each K⩾1, there exists and equivalent K times faster nondeterministic Turing machine M′ writing only zeroes and ones on its tape. In other words, we can obtain the linear speed-up while preserving the binary worktape alphabet. Therefore, nondeterministic single-tape Turing machines do not require tape compression for speeding up