English

On the questions P ?= NP $\cap$ co-NP and NP ?= co-NP for infinite time Turing machines

Logic 2007-05-23 v1

Abstract

Schindler recently addressed two versions of the question P =?\stackrel{?}{=} NP for Turing machines running in transfinite ordinal time. These versions differ in their definition of input length. The corresponding complexity classes are labelled P, NP and P+,NP+{\rm P}^+,{\rm NP}^+. Schindler showed that P \neq NP and P+NP+{\rm P}^+ \neq {\rm NP}^+. We show that P == NP \cap co-NP and NP \neq co-NP, whereas P+{\rm P}^+ \subset NP \cap co-NP and NP+{\rm NP}^+ \neq co-NP+^+.

Keywords

Cite

@article{arxiv.math/0305445,
  title  = {On the questions P ?= NP $\cap$ co-NP and NP ?= co-NP for infinite time Turing machines},
  author = {Vinay Deolalikar},
  journal= {arXiv preprint arXiv:math/0305445},
  year   = {2007}
}

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9 pages