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|    sci.logic    |    Logic -- math, philosophy & computationa    |    262,912 messages    |
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|    Message 261,916 of 262,912    |
|    olcott to Richard Damon    |
|    Re: Exactly what halt deciders actually     |
|    14 Dec 25 21:32:54    |
      XPost: comp.theory, sci.math, comp.theory       From: polcott333@gmail.com              On 12/14/2025 7:56 PM, Richard Damon wrote:       > On 12/14/25 8:17 PM, olcott wrote:       >> On 12/14/2025 7:00 PM, Richard Damon wrote:       >>> On 12/14/25 7:31 PM, olcott wrote:       >>>> Whenever any textbook says that a halt decider       >>>> must compute halting for machine M on input w       >>>> is it wrong. At best it only computes the halting       >>>> of M/w through the proxy of finite strings ⟨M⟩/w.       >>>       >>> Nope, you are just wrong because you are too stupid to understand       >>> representations.       >>>       >>       >> You already agreed to this, you didn't bother       >> to pay close enough attention to the paraphrase       >> of what you already agreed to.       >>       >> Halt deciders report on the behavior of       >> Turing machines only through the proxy       >> of finite string machine descriptions.       >>       >> Whenever textbooks do not say it exactly that       >> way they are being less than completely accurate.       >       > Nope, and thus you show you don't understand how language works.       >       > The fact that the text you read weren't explicit enough              Proves that they are not as precise as they could be.       That lack of precision leads to universal misconception.              > for you just       > shows that likely you don't have the needed background for them, and       > that fact was presumed already known by the student.       >       > Just like a calculus book won't explicitly warn you that division by 0       > is just undefined, or that multiplication by 1 is a no operation.       >       >>       >>>>       >>>> Turing machine deciders compute the mapping from       >>>> input finite strings to an accept or reject value       >>>> by some criterion measure.       >>>       >>> Right, and for a Halt Decider, that criteria is the behavior of the       >>> machine the input string represents.       >>>       >>       >> There is a key semantic difference between       >> finite string x has a syntactic property       >> and finite string x specifies a semantic property       >       > yes, and that is part of the problem. Finite machine deciders can only       > compute syntactic operations.       >              Then Rice's theorem is tossed out the window?              In computability theory, Rice's theorem states       that all non-trivial semantic properties of       programs are undecidable. A semantic property       is one about the program's behavior              https://en.wikipedia.org/wiki/Rice%27s_theorem              > Questions can be about semantics.       >       > To make a decider, you need to find the algorithmic bridge between the       > two of them.       >       > For instance, Proof VERIFICATION, which is a semantic operation, can be       > reduced to syntactic steps, and thus we can build a Machine to see if a       > given input it a proper proof, and said machine can work for all input       > string.       >              Here is an insight that LLM Kimi suggested entirely       on the basis of the text of my first principles.              The Universal TM's Illusion: The UTM appears       to "simulate another machine," but it's really just       interpreting a string as a lookup table for state       transitions. The simulation is pure string rewriting.              > But, what cant' be done is to write a machine that takes a proposition       > and tells you if it is provable, as that can not be converted into a       > syntactic operation.       >       >                     --       Copyright 2025 Olcott |
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