Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: olcott Newsgroups: comp.theory Subject: Re: How do computations actually work? Date: Fri, 23 May 2025 11:04:49 -0500 Organization: A noiseless patient Spider Lines: 89 Message-ID: <100q6b1$5buc$2@dont-email.me> References: <95db078e80b2868ed15a9a9a2af0280d96234a3a@i2pn2.org> <100jo18$2mhfd$1@dont-email.me> <100jpv9$2m0ln$4@dont-email.me> <100kt0c$2tae8$3@dont-email.me> <100ktr7$2reaa$1@dont-email.me> <100l09v$2tae8$5@dont-email.me> <100l1ov$2ul3j$1@dont-email.me> <100l3jh$2v0e9$1@dont-email.me> <100l5c8$2ul3j$2@dont-email.me> <100l75g$2vpq3$1@dont-email.me> <100l887$2ul3i$2@dont-email.me> <100l9gh$30aak$1@dont-email.me> <100lc4o$30pgm$1@dont-email.me> <100ld1u$312c9$1@dont-email.me> <100lg4g$31jt3$1@dont-email.me> <100lkdv$32ib3$1@dont-email.me> <100lmif$32v06$1@dont-email.me> <100lmp3$32ven$1@dont-email.me> <100m319$38k55$2@dont-email.me> <87jz69xlpx.fsf@nosuchdomain.example.com> <100mder$39slu$2@dont-email.me> <100oipb$3oge1$1@dont-email.me> <100onkd$3t5cb$1@dont-email.me> <100p6vj$3vlgq$1@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 23 May 2025 18:04:50 +0200 (CEST) Injection-Info: dont-email.me; posting-host="4606f99203c21d5702beb16569e2a0e8"; logging-data="176076"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+7C1vqheHp7P6N8K4n32Ee" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:+19CUOSO9iER/vsWXvro95TsdXc= In-Reply-To: <100p6vj$3vlgq$1@dont-email.me> X-Antivirus-Status: Clean X-Antivirus: Norton (VPS 250523-2, 5/23/2025), Outbound message Content-Language: en-US On 5/23/2025 2:09 AM, Mikko wrote: > On 2025-05-23 02:47:40 +0000, olcott said: > >> On 5/22/2025 8:24 PM, Mike Terry wrote: >>> On 22/05/2025 06:41, Richard Heathfield wrote: >>>> On 22/05/2025 06:23, Keith Thompson wrote: >>>>> Richard Heathfield writes: >>>>>> On 22/05/2025 00:14, olcott wrote: >>>>>>> On 5/21/2025 6:11 PM, Richard Heathfield wrote: >>>>> [...] >>>>>>>> Turing proved that what you're asking is impossible. >>>>>>>> >>>>>>> That is not what he proved. >>>>>> >>>>>> Then you'll be able to write a universal termination analyser that >>>>>> can >>>>>> correctly report for any program and any input whether it halts. Good >>>>>> luck with that. >>>>> >>>>> Not necessarily. >>>> >>>> Of course not. But I'm just reflecting. He seemed to think that my >>>> inability to write the kind of program Turing envisaged (an >>>> inability that I readily concede) is evidence for his argument. >>>> Well, what's sauce for the goose is sauce for the gander. >>>> >>>>> Even if olcott had refuted the proofs of the >>>>> insolvability of the Halting Problem -- or even if he had proved >>>>> that a universal halt decider is possible >>>> >>>> And we both know what we both think of that idea. >>>> >>>>> -- that doesn't imply >>>>> that he or anyone else would be able to write one. >>>> >>>> Indeed. >>>> >>>>> I've never been entirely clear on what olcott is claiming. >>>> >>>> Nor I. Mike Terry seems to have a pretty good handle on it, but no >>>> matter how clearly he explains it to me my eyes glaze over and I >>>> start to snore. >>> >>> Hey, it's the way I tell 'em! >>> >>> Here's what the tabloids might have said about it, if it had made the >>> front pages when the story broke: >>> >>>   COMPUTER BOFFIN IS TURING IN HIS GRAVE! >>> >>>   An Internet crank claims to have refuted Linz HP proof by creating a >>>   Halt Decider that CORRECTLY decides its own "impossible input"! >>>   The computing world is underwhelmed. >>> >>> Better?  (Appologies for the headline, it's the best I could come up >>> with.) >>> >>> Mike. >>> >> >> There is a key detail about ALL of these proofs >> that no one has paid attention to for 90 years. >> >> It is impossible to define *AN INPUT* to HHH that >> does the opposite of whatever value that HHH returns. > > That is a key detail about HHH. Your HHH is not a part of those proofs. All of the proofs work this same way. It is merely much easier to see in a fully defined and fully operational language such as C/x86. > For every Turing machine presented as a halting decider it is possible > to construct a computation that that Turing machine cannot decide > correctly. If that computation cannot be presented as an input to HHH > then HHH is not a halting decider. > int main() { DD(); // Try to show how HHH called by DD can report } // on the behavior of its caller. HHH is not (and is not supposed to be) a halt decider for its caller. That is just not the way that computations work. -- Copyright 2025 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer