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|    Message 262,741 of 262,912    |
|    olcott to Mikko    |
|    Re: The Halting Problem asks for too muc    |
|    27 Jan 26 09:29:23    |
      XPost: sci.math, comp.theory       From: polcott333@gmail.com              On 1/27/2026 2:15 AM, Mikko wrote:       > On 26/01/2026 18:45, 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?       >              A meta level is even required to prove what is true       in actual PA. This meta-level does a back-chained       inference from x to the axioms of PA.              > In the metatheory one can construct a model of PA. Everyting in that       > model can be proven in the metatheory is true in that model so it is       > true in some model of PA.       >              Yes I am making sure to exclude that. Confusion between       what is actually true in actual PA and what is true in       separate models of arithmetic is how the misconception       of incompleteness arose.              >> I thought you said that PA had to be able to determine the truth itself?       >              PA doesn't even have a provability operator so we need       a meta-level for that. Unlike how it is conventionally       done I exclude the standard model of arithmetic completely.              Any expression not derivable from the axioms of PA is       non-well-founded in PA. The misconception of incompleteness       only arose because true in PA was incorrectly conflated       with true in the standard model of arithmetic.              > No, I said it doesn't. But what is provable in first order PA is true in       > every model of first order PA and what is not provable in PA is false in       > some model of first order PA. But there is no known way to extend this       > result to the second order, and the original PA is a sencond order       > theory.       >                     --       Copyright 2026 Olcott |
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