P ≠ NP ∩ co-NP for Infinite Time Turing Machines
Vinay Deolalikar, Joel David Hamkins, Ralf Schindler · Journal of Logic and Computation · 2005
Extending results of Schindler, Hamkins and Welch, we establish in the context of infinite time Turing machines that P is properly contained in NP ∩ co-NP. For higher analogues of these classes, we exhibit positive and negative results.