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|    Message 262,757 of 262,912    |
|    olcott to Mikko    |
|    Re: The Halting Problem asks for too muc    |
|    29 Jan 26 07:57:29    |
      XPost: comp.theory, sci.math       From: polcott333@gmail.com              On 1/29/2026 3:12 AM, Mikko wrote:       > On 28/01/2026 15:49, olcott wrote:       >> On 1/28/2026 3:54 AM, Mikko wrote:       >>> On 27/01/2026 17:32, olcott wrote:       >>>> On 1/27/2026 2:17 AM, Mikko wrote:       >>>>> On 26/01/2026 18:58, olcott wrote:       >>>>>> On 1/26/2026 10:45 AM, Richard Damon wrote:       >>>>>>> On 1/26/26 10:22 AM, olcott wrote:       >>>>>>>> On 1/26/2026 6:55 AM, Mikko wrote:       >>>>>>>>> On 25/01/2026 15:30, olcott wrote:       >>>>>>>>>> On 1/25/2026 5:24 AM, Mikko wrote:       >>>>>>>>>>> On 24/01/2026 16:18, olcott wrote:       >>>>>>>>>>>> On 1/24/2026 2:23 AM, Mikko wrote:       >>>>>>>>>>>>> On 22/01/2026 18:47, olcott wrote:       >>>>>>>>>>>>>> On 1/22/2026 2:21 AM, Mikko wrote:       >>>>>>>>>>>>>       >>>>>>>>>>>>>>> Anyway, what can be provven that way is true aboout PA.       >>>>>>>>>>>>>>> You can deny       >>>>>>>>>>>>>>> the proof but you cannot perform what is meta-provably       >>>>>>>>>>>>>>> impossible.       >>>>>>>>>>>>>       >>>>>>>>>>>>>> The meta-proof does not exist in the axioms of PA       >>>>>>>>>>>>>> and that is the reason why an external truth in       >>>>>>>>>>>>>> an external model cannot be proved internally in PA.       >>>>>>>>>>>>>> All of these years it was only a mere conflation       >>>>>>>>>>>>>> error.       >>>>>>>>>>>>>       >>>>>>>>>>>>> It is perfectly clear which is which. But every proof in PA       >>>>>>>>>>>>> is also       >>>>>>>>>>>>> a proof in Gödel's metatheory.       >>>>>>>>>>>>       >>>>>>>>>>>> ∀x ∈ PA ( True(PA, x) ≡ PA ⊢ x )       >>>>>>>>>>>> ∀x ∈ PA ( False(PA, x) ≡ PA ⊢ ¬x )       >>>>>>>>>>>> ∀x ∈ PA ( ¬WellFounded(PA, x) ≡       >>>>>>>>>>>> (¬True(PA, x) ∧ (¬False(PA, x)))       >>>>>>>>>>>       >>>>>>>>>>> Those sentences don't mean anything without specificantions of a       >>>>>>>>>>> language and a theory that gives them some meaning.       >>>>>>>>>>       >>>>>>>>>> In other word you do not understand standard notational       >>>>>>>>>> conventions that define True for PA as provable from the       >>>>>>>>>> axioms of PA and False for PA as refutable from the axioms       >>>>>>>>>> of PA.       >>>>>>>>>       >>>>>>>>> There are no notational convention that defines True, False, and       >>>>>>>>> WellFounded with two arguments. And you did not specify in which       >>>>>>>>> context your sentences are true or otherwise relevant.       >>>>>>>>>       >>>>>>>>       >>>>>>>> “x is a single finite string representing       >>>>>>>> a PA‑formula, such as ‘2 + 3 = 5’.       >>>>>>>> True(PA, x), False(PA, x), and WellFounded(PA, x)       >>>>>>>> are meta‑level unary predicates classifying       >>>>>>>> that formula by its provability in PA.”       >>>>>>>>       >>>>>>>       >>>>>>> In outher words, you ACCEPT that the meta level can define what       >>>>>>> is true in PA?       >>>>>>>       >>>>>>> I thought you said that PA had to be able to determine the truth       >>>>>>> itself?       >>>>>>       >>>>>> We need a meta-level truth predicate anchored       >>>>>> only in the axioms of PA itself and thus not       >>>>>> anchored in the standard model of arithmetic.       >>>>>       >>>>> That predicate is not computable.       >>>>       >>>> That was Tarski's mistake.       >>>       >>> No, Tarski's proof is about a different problem, though the results       >>> are related and there are much similarity in the proofs. Tarski did       >>> not use Turing machines in the proof but a computability proof must       >>> use that.       >>       >> Because you refuse to understand the underlying       >> details of what occurs_check means I cannot       >> explain to you how Tarski erred.       >       > Irrelevant. There is no "occurs_check" in Tarski's proof.       >              If there was then there never would be a Tarski proof.       https://liarparadox.org/Tarski_247_248.pdf              --       Copyright 2026 Olcott |
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