• UTM Theorem vs the identity function

    From Tristan Wibberley@tristan.wibberley+netnews2@alumni.manchester.ac.uk to comp.theory on Tue Oct 21 17:35:50 2025
    From Newsgroup: comp.theory

    The message body is Copyright (C) 2025 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except as noted in
    the sig.


    If the UTM Theorem states there's a u such that u(e,x) = f(x) where both
    are defined and both are undefined when either is undefined, is that interesting or surprising to anybody?

    The identity function is valid for u and forces that e = f. Job done.

    Am I missing something? Isn't it just trivially deducible from the
    identity introduction axiom when you have it, which we assume when we
    haven't fully formalised our discussion of computation.

    --
    Tristan Wibberley

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  • From pa@pa@see.signature.invalid (Pierre Asselin) to comp.theory on Tue Oct 21 18:50:43 2025
    From Newsgroup: comp.theory

    Tristan Wibberley <tristan.wibberley+netnews2@alumni.manchester.ac.uk> wrote:

    If the UTM Theorem states there's a u such that u(e,x) = f(x) where both
    are defined and both are undefined when either is undefined, is that interesting or surprising to anybody?

    Replace "there's a u" by "there is a u such that for all f there is an e"

    The identity function is valid for u and forces that e = f. Job done.

    * u is a computable function;
    * f is a computable function;
    * e is the Gödel number of a Turing machine that computes f.
    How can e and f be equal ?
    --
    pa at panix dot com
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  • From Tristan Wibberley@tristan.wibberley+netnews2@alumni.manchester.ac.uk to comp.theory on Wed Oct 22 03:48:01 2025
    From Newsgroup: comp.theory

    On 21/10/2025 19:50, Pierre Asselin wrote:
    Tristan Wibberley <tristan.wibberley+netnews2@alumni.manchester.ac.uk> wrote:

    * u is a computable function;
    * f is a computable function;
    * e is the Gödel number of a Turing machine that computes f.
    How can e and f be equal ?


    That damned wikipedia again. It didn't constrain e to Goedel numbers.
    There appears to be a trend of having wikipedia leave out key
    constraints thus making its statements about formalised things be
    universally qualified when they shouldn't be and therefore untrue.


    --
    Tristan Wibberley

    The message body is Copyright (C) 2025 Tristan Wibberley except
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  • From olcott@polcott333@gmail.com to comp.theory on Tue Oct 21 21:51:16 2025
    From Newsgroup: comp.theory

    On 10/21/2025 9:48 PM, Tristan Wibberley wrote:
    On 21/10/2025 19:50, Pierre Asselin wrote:
    Tristan Wibberley <tristan.wibberley+netnews2@alumni.manchester.ac.uk> wrote:

    * u is a computable function;
    * f is a computable function;
    * e is the Gödel number of a Turing machine that computes f.
    How can e and f be equal ?


    That damned wikipedia again. It didn't constrain e to Goedel numbers.
    There appears to be a trend of having wikipedia leave out key
    constraints thus making its statements about formalised things be
    universally qualified when they shouldn't be and therefore untrue.


    Gödel numbers totally hide the underlying semantics.


    --
    Tristan Wibberley

    The message body is Copyright (C) 2025 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

    --
    Copyright 2025 Olcott "Talent hits a target no one else can hit; Genius
    hits a target no one else can see." Arthur Schopenhauer
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  • From Tristan Wibberley@tristan.wibberley+netnews2@alumni.manchester.ac.uk to comp.theory on Wed Oct 22 04:02:10 2025
    From Newsgroup: comp.theory

    On 22/10/2025 03:51, olcott wrote:
    Gödel numbers totally hide the underlying semantics.

    I bet they /do/ !

    --
    Tristan Wibberley

    The message body is Copyright (C) 2025 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
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    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
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  • From olcott@polcott333@gmail.com to comp.theory on Tue Oct 21 22:35:43 2025
    From Newsgroup: comp.theory

    On 10/21/2025 10:02 PM, Tristan Wibberley wrote:
    On 22/10/2025 03:51, olcott wrote:
    Gödel numbers totally hide the underlying semantics.

    I bet they /do/ !


    The most important aspect of Gödel's 1931 Incompleteness theorem
    are these plain English direct quotes of Gödel from his paper:

    ...there is also a close relationship with the “liar” antinomy,14 ...
    ...14 Every epistemological antinomy can likewise be used for a similar undecidability proof...
    ...We are therefore confronted with a proposition which asserts its own unprovability. 15 ...
    (Gödel 1931:40-41)

    Gödel, Kurt 1931.
    On Formally Undecidable Propositions of Principia Mathematica And
    Related Systems

    ?- LP = not(true(LP)).
    LP = not(true(LP)).

    ?- unify_with_occurs_check(LP, not(true(LP))).
    false.

    https://www.researchgate.net/publication/331859461_Minimal_Type_Theory_YACC_BNF


    LP := ~True(LP)
    00 ~ 01
    01 True 00

    In both Prolog and Olcott's Minimal Type Theory
    a cycle is detected in the evaluation sequence
    of the formalized: "This sentence is not true"

    Since Gödel said
    ...14 Every epistemological antinomy can likewise be used for a similar undecidability proof...

    We simply reject G := ¬(F ⊢ G)
    before it even gets started.

    --
    Tristan Wibberley

    The message body is Copyright (C) 2025 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

    --
    Copyright 2025 Olcott "Talent hits a target no one else can hit; Genius
    hits a target no one else can see." Arthur Schopenhauer
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  • From Mikko@mikko.levanto@iki.fi to comp.theory on Wed Oct 22 12:39:16 2025
    From Newsgroup: comp.theory

    On 2025-10-21 16:35:50 +0000, Tristan Wibberley said:

    The message body is Copyright (C) 2025 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except as noted in
    the sig.

    If the UTM Theorem states there's a u such that u(e,x) = f(x) where both
    are defined and both are undefined when either is undefined, is that interesting or surprising to anybody?

    The identity function is valid for u and forces that e = f. Job done.

    No, the inference that e = f is not correct. But somehing is missing
    from the above. Without further deails the above simply says that
    u(e, x) does not depend on e, i.e., that it has the same value f(x)
    for every e. But that has nothing to do with any theorem about UTM's.
    --
    Mikko

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  • From Tristan Wibberley@tristan.wibberley+netnews2@alumni.manchester.ac.uk to comp.theory on Wed Oct 22 12:05:40 2025
    From Newsgroup: comp.theory

    On 22/10/2025 10:39, Mikko wrote:
    [something] is missing
    from the above. Without further deails the above simply says that
    u(e, x) does not depend on e, i.e., that it has the same value f(x)
    for every e. But that has nothing to do with any theorem about UTM's.

    The description I read, from wikipedia, did not include the constraint
    that e is a Goedel number. I corrected that element.


    --
    Tristan Wibberley

    The message body is Copyright (C) 2025 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
    any production AI system with it but you may train experimental AI that
    will only be used for evaluation of the AI methods it implements.

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  • From pa@pa@see.signature.invalid (Pierre Asselin) to comp.theory on Wed Oct 22 18:45:22 2025
    From Newsgroup: comp.theory

    Tristan Wibberley <tristan.wibberley+netnews2@alumni.manchester.ac.uk> wrote:

    That damned wikipedia again. It didn't constrain e to Goedel numbers.

    Quoting from the Wikipedia article "UTM theorem":

    The theorem states that a partial computable function u of
    two variables exists such that, for every computable function
    f of one variable, a Goedel number e exists such that f (
    x ) ? u ( e , x ) {\displaystyle f(x)\simeq u(e,x)} for
    all x.

    Notice the phrase "a Goedel number e". Were you reading some other
    article?
    --
    pa at panix dot com
    This self-referential copyright notice is in the public domain.
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  • From Tristan Wibberley@tristan.wibberley+netnews2@alumni.manchester.ac.uk to comp.theory on Thu Oct 23 03:34:50 2025
    From Newsgroup: comp.theory

    On 22/10/2025 19:45, Pierre Asselin wrote:
    Tristan Wibberley <tristan.wibberley+netnews2@alumni.manchester.ac.uk> wrote:

    That damned wikipedia again. It didn't constrain e to Goedel numbers.

    Quoting from the Wikipedia article "UTM theorem":
    [snip]
    Notice the phrase "a Goedel number e". Were you reading some other
    article?


    Yes, I was reading the slightly different article that was at the same
    location 24 hours earlier, some hours before I adjusted it to show the
    words "a Goedel number" that you quoted after having been educated on
    the matter in your message news:10d8cp6$26v9$1@dont-email.me.

    --
    Tristan Wibberley

    The message body is Copyright (C) 2025 Tristan Wibberley except
    citations and quotations noted. All Rights Reserved except that you may,
    of course, cite it academically giving credit to me, distribute it
    verbatim as part of a usenet system or its archives, and use it to
    promote my greatness and general superiority without misrepresentation
    of my opinions other than my opinion of my greatness and general
    superiority which you _may_ misrepresent. You definitely MAY NOT train
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  • From Mikko@mikko.levanto@iki.fi to comp.theory on Thu Oct 23 11:12:33 2025
    From Newsgroup: comp.theory

    On 2025-10-22 11:05:40 +0000, Tristan Wibberley said:

    On 22/10/2025 10:39, Mikko wrote:
    [something] is missing
    from the above. Without further deails the above simply says that
    u(e, x) does not depend on e, i.e., that it has the same value f(x)
    for every e. But that has nothing to do with any theorem about UTM's.

    The description I read, from wikipedia, did not include the constraint
    that e is a Goedel number. I corrected that element.

    That does not help. The point is that in the UTM theorem the equation
    is not claimed to be true for every e, only that for each f there
    is at least one e for which the equation is true. In addition, as
    u is required to be computable, e must be of a type that can be an
    argument to a computable fuction, which by usual definitions excludes functions.
    --
    Mikko

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