Can we construct an explicit Turing Machine with a Halt1 oracle that decides if a standard Turing Machine halts on all inputs?

By a Halt1 oracle I mean that we have the ability to decide if Turing Machines with a Halting oracle halts or not.


1 Answer 1


I think that I have an answer to this, putting together my question helped me clarify things enough to come up with this idea

def X(T : TM0):
   for n = 0 and up:
      if !Halt0('T(n)')

Now if we ask Halt1('X(T)') we should get an answer

  • yes => T diverges on some input
  • no => T halts on all inputs

Does this all make sense logically?


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