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From: "Fred. Zwarts" <F.Zwarts@HetNet.nl>
Newsgroups: comp.theory
Subject: Re: Flibble's Law
Date: Sat, 19 Apr 2025 10:40:05 +0200
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Op 19.apr.2025 om 04:40 schreef olcott:
> On 4/18/2025 8:38 PM, Mike Terry wrote:
>> On 19/04/2025 00:19, Keith Thompson wrote:
>>> Richard Damon <richard@damon-family.org> writes:
>>>> On 4/18/25 5:16 PM, Mr Flibble wrote:
>>> [...]
>>>>> I'm not claiming we can build a decider with infinite resources.
>>>>> I'm saying that if the problem permits infinite machines, then
>>>>> infinite analyzers are fair game in theory.
>>>>
>>>> No, you don't get to say that.
>>>
>>> Well, actually ...
>>>
>>> Sure, Mr. Flibble gets to say anything he likes.  Anyone can
>>> define a mathematical system with any consistent rules they like,
>>> and derive results that apply within that system.
>>>
>>>>> The Flibble Reciprocity Principle:
>>>>> In theoretical computation, every permitted infinity in problem
>>>>> formulation implies a permitted infinity in problem analysis.
>>>>> It's about playing the game by the rules of the game.
>>>>
>>>> No, it is making up your own rules and admittion that you think
>>>> cheating is ok.
>>>>
>>>> The "Rules" exist, and are defined, and they say that decider do NOT
>>>> get infinite time.
>>>
>>> The "Rules" are fundamentally arbitrary (but ideally chosen for
>>> their relevance to the real world).  Defining a new set of rules
>>> is how we got useful and/or interesting things like non-Euclidean
>>> geometry and complex numbers.
>>>
>>> The flaw in Flibble's reasoning is that he claims that some kind of
>>> "fair game" principle implies that he can make certain specific
>>> rule changes.  I suggest that he doesn't need that excuse.
>>>
>>> The rules under which most of us operate, and in which the Halting
>>> Problem proof was constructed, are designed to correspond to
>>> real-world computational models (with some simplifications like
>>> not limiting storage size).
>>>
>>> Mr. Flibble, I think, is inventing new rules because he doesn't like
>>> the results from the existing rules.  I think he dislikes the fact
>>> that the Halting Problem is not solvable, and is trying to define a
>>> new system in which it's solvable in some sense.  And sure, he can
>>> (try to) do that if he likes.  But it's worth spending time on that
>>> *only* if the results of the new rules are interesting and/or useful.
>>> It's also a good thing if the new rules are clearly defined, for
>>> example rigorously defining what a "pathological input" is.
>>>
>>> It would also be nice if Mr. Flibble acknowledged that the proof of
>>> the unsolvability of the Halting Problem is valid within the usual
>>> set of rules (and that he understands those rules), rather than
>>> implying that the proof is invalid because the rules are "unfair"
>>> or something.
>>>
>>
>> I'm not convinced Mr.Flibble has had a proper shot at understanding 
>> the halting problem as it is properly stated (in mathematics / 
>> computer science).  Also I think he is far more sensible than PO, when 
>> it comes to understanding what's being said in an argument, although 
>> also it has to be said that's a very low bar...
>>
>> I suspect Mr.Flibble's only visibility of HP has come via a 
>> combination of C.Strachey's "An impossible program" article, and PO 
>> threads on these newsgroups!  He might be forgiven for getting the 
>> wrong impression over issues of self reference etc., and he freely 
>> admitted on his first PO- thread posting that he was quite new to HP.  
>> Unlike PO, I'm pretty sure he has actually changed his opinion about 
>> something(?) once he understood the background better.  PO has no 
>> prospect of ever undertanding the background of anything technical 
>> like HP.
>>
>> So a great thing for Mr.Fibble to do would be to forget everything in 
>> Strachey's correspondence and everything that PO has said on these 
> 
> As I remember is Flibble first heard of the Halting Problem
> from me and that was probably my Strachey Link.
> 
> https://academic.oup.com/comjnl/article-abstract/7/4/313/354243? 
> redirectedFrom=fulltext
> 
>> newsgroups about "pathelogical self reference" etc., and go back to 
>> reading e.g. Linz's HP proof to understand what HP says and the proof 
>> in particular.  PO has extracted the half a dozen or so pages from the 
>> Linz proof into a PDF which he has published somewhere, probably on 
>> ResearchGate.  [I'm sure I could find this if PO doesn't chip in with 
>> details]
>>
> 
> https://www.liarparadox.org/Peter_Linz_HP_317-320.pdf
> 
>> If Mr.Flibble went back to a proper HP problem statement he might 
>> hopefully realise that the "pathelogical" self-reference is not of a 
>> type that is of any concern, due to the order things are done in the 
>> proper HP proof.  It is no different from the kind of self reference 
>> we see e.g. in a backup utility backing up its own source code, or 
>> even backing up its own executable file. 
> 
> int DD()
> {
>    int Halt_Status = HHH(DD);
>    if (Halt_Status)
>      HERE: goto HERE;
>    return Halt_Status;
> }
> 
> *The input to HHH(DD) specifies recursive emulation*
> Lying about this or changing the subject to a different
> instance of than DD emulated by HHH using will be
> ridiculed as dishonest or stupid.
> 
> That the finite string given to HHH specifies a halting program 
according to the semantics of the x86 language is proven when exactly 
the same string is used for direct execution or world-class simulators.
This finite string specifies only one program with only one behaviour, 
according to the semantics of the x86 language.
The input to HHH(DD) is DD including all the functions it uses, 
including HHH itself. When we understand that, we see that this input 
specifies only a *finite* recursive emulation, because after a few 
cycles, the simulation is aborted. Changing this input to a hypothetical 
other input that does not abort is just as dishonest or stupid as saying 
that Sum(2,3) is correct to return 9, because it uses the hypothetical 
inputs 4 and 5.
HHH should use its actual input (whichs aborts), not the hypotetical 
input that does not abort.
But I think that we agree that there is no algorithm that can determine 
for all possible inputs whether the input specifies a program that 
(according to the semantics of the machine language) halts when directly 
executed?
Correct?