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|    Message 262,838 of 262,912    |
|    olcott to Richard Damon    |
|    Re: When halt provers are allowed to rej    |
|    07 Feb 26 09:08:56    |
      XPost: comp.theory       From: polcott333@gmail.com              On 2/7/2026 8:44 AM, Richard Damon wrote:       > On 2/7/26 8:08 AM, olcott wrote:       >> On 2/7/2026 4:15 AM, Mikko wrote:       >>> On 06/02/2026 17:32, olcott wrote:       >>>> On 2/6/2026 3:15 AM, Mikko wrote:       >>>>> On 05/02/2026 13:28, olcott wrote:       >>>>>       >>>>>> On 2/5/2026 4:45 AM, Mikko wrote:       >>>>>>> On 04/02/2026 18:47, olcott wrote:       >>>>>>>       >>>>>>>> A halt prover attempts to prove halting       >>>>>>>       >>>>>>> To prove that a computation halts is simple. Just show the execution       >>>>>>> trace from the start to the halting. The hard problem is to prove       >>>>>>> that an execution does not halt.       >>>>>>>       >>>>>>>> and when it detects that the proof of its input does not form       >>>>>>>>       >>>>>>>> *a well-founded justification tree within Proof*       >>>>>>>> *theoretic semantics*       >>>>>>>>       >>>>>>>> Then it is correct to reject this input as bad data.       >>>>>>>       >>>>>>> No, that does not follow. That only means that it is correct to       >>>>>>> reject       >>>>>>> the proof. The conclusion of the proof may still be correct.       >>>>>> The way that proofs work in proof theoretic       >>>>>> semantics is that they reject inputs not having       >>>>>> well-founded justification trees as bad data.       >>>>>       >>>>> An example of a valid input is "42". That input has no justification,       >>>>> well-founded or otherwise. But there is no proof that would reject       >>>>> "42" as bad data.       >>>>       >>>> It is an element of the set of natural numbers.       >>>       >>> True, but non necessarily relevant to tthe proof. But the current       >>> question is whether the proof rejects the input "42" as bad data.       >>>       >>       >> Is the integer 42 a machine description that halts?       >> Reject.       >>       >       > But 42 might well be a machine description that halts, it depend on how       > you have defined your encoding of a machine.              Can't be the shortest one is a single quintuple.              --       Copyright 2026 Olcott |
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