Forums before death by AOL, social media and spammers... "We can't have nice things"
|    sci.logic    |    Logic -- math, philosophy & computationa    |    262,912 messages    |
[   << oldest   |   < older   |   list   |   newer >   |   newest >>   ]
|    Message 262,740 of 262,912    |
|    Mikko to olcott    |
|    Re: The Halting Problem asks for too muc    |
|    27 Jan 26 10:05:05    |
      XPost: comp.theory, sci.math       From: mikko.levanto@iki.fi              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.              --       Mikko              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
[   << oldest   |   < older   |   list   |   newer >   |   newest >>   ]
(c) 1994, bbs@darkrealms.ca