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|    sci.logic    |    Logic -- math, philosophy & computationa    |    262,912 messages    |
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|    Message 262,678 of 262,912    |
|    olcott to Richard Damon    |
|    =?UTF-8?Q?Re=3A_G=C3=B6del=27s_G_has_nev    |
|    22 Jan 26 19:05:39    |
      XPost: comp.theory, sci.math, comp.ai.philosophy       From: polcott333@gmail.com              On 1/22/2026 6:23 PM, Richard Damon wrote:       > On 1/20/26 6:33 PM, olcott wrote:       >> On 1/20/2026 5:08 PM, Tristan Wibberley wrote:       >>> On 18/01/2026 23:41, olcott wrote:       >>>       >>>> I already just said that the proof and refutation of       >>>> Goldbach are outside the scope of PA axioms.       >>>       >>> So Richard is right that you need a truth value for not being covered:       >>>       >>> True(S, Goldbach) = OutOfScope       >>>       >>> or a type theory to give True(S, Goldbach) no content when Goldbach is       >>> out of scope, or keep it explicit with an InScope(S, P) family of       >>> propositions. Of course, the type theory approach is often easier to use       >>> with pencil and paper.       >>>       >>       >> ∀x ∈ PA ((True(PA, x) ≡ (PA ⊢ x))       >> ∀x ∈ PA ((False(PA, x) ≡ (PA ⊢ ~x))       >>       >> In PA itself this requires pathological self-reference to       >> be computed in meta-math by detecting a cycle in the       >> directed graph of the evaluation sequence of the expression.       >> This seems to block all of the undecidability that would       >> otherwise be construed as incompleteness.       >       > Which just shows that you are a liar, as the relaitionship in PA doesn't       > refer to itself.       >       > You think you are allowed to equivocate on your use of looking into the       > meta-system.       >       >>       >> ∀x ∈ PA (~WellFounded(PA, x) ≡ (~True(PA, x) ∧ (~False(PA, x))       >       > For which there is no Proof-Theoretic resolution of, and thus no       > handling in Proof-Theoretic semantics.       >       >>       >> It is also best that an outer knowledge level resolve       >> Goldbach as outside of the domain of knowledge. If not       >> then PA might try brute force ans get stuck in a loop.       >> So within the domain of knowledge Goldbach is ~WellFounded.       >       > But that isn't true, there is no knowledge of that fact, ax we don't       > know if it can be proven or refuted.       >       > In fact, it CAN'T be proved to be not-well-founded in PA, as proving       > that we can't disprove it ends up proving it.       >       > The problem is that some statements are inherently logically truth-       > beares, as there can be no middle to try to exclude, but they also might       > not be provable.       >       > Your Proof-Theoretic Semantics concept can't handle systems where that       > is a fact.       >       >>       >>> Is there a conventional alternative to implication for an explicit       >>> alternative of type theory?       >>>       >>> Unsatisfying: WhenInScope(S, P) -> (True(S, P) & Foo(P))       >>> More satisfying: WhenInScope(S,P,Q in (True(S,Q) & Foo(Q)))       >>>       >>> Hey, I see that in prolog often. Q is an indeterminate (unbound variable       >>> in prolog) bound by WhenInScope(S,P,Q in ...) within "...".       >>>       >>> or a lambda expression alternative:       >>>       >>> WhenInScope(S,P,λQ.True(S,Q) & Foo(Q))       >>>       >>> I prefer that over an implicit, semi-ad-hoc type theory.       >>>       >>> Are there conventional names for these ideas and an author and excellent       >>> exposition textbook?       >>>       >>       >> Well-founded proof theoretic semantics.       >>       >>       >       > So, have a reference that uses it the way you do, or are you admitting       > that it is you own cockamamie perversion of a system that works for the       > things it works for but not this sort of system.       >               From “Intuitionistic Type Theory” (1984), p. 7)       “To know a proposition is true is to know a proof of it.”              --       Copyright 2026 Olcott |
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