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|    Message 262,743 of 262,912    |
|    olcott to Mikko    |
|    Re: The Halting Problem asks for too muc    |
|    27 Jan 26 08:48:53    |
      XPost: comp.theory, sci.math       From: polcott333@gmail.com              On 1/27/2026 2:05 AM, Mikko wrote:       > On 26/01/2026 17:22, 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.”       >       > The above is not a notational convention. The symbols may be defined       > in some context but they are undefined elsewhere.       >              Mendelson simply uses ⊢ 𝒞 to indicate that 𝒞 is a theorem.       ∀x (True(x) ≡ ⊢ 𝒞)                            --       Copyright 2026 Olcott |
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