Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: Mikko Newsgroups: comp.theory Subject: Re: How do computations actually work? Date: Tue, 27 May 2025 11:29:40 +0300 Organization: - Lines: 119 Message-ID: <1013t5k$2hgid$1@dont-email.me> References: <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> <100q6b1$5buc$2@dont-email.me> <100rtvq$ji9l$1@dont-email.me> <100sod2$p071$6@dont-email.me> <100umo8$1a058$1@dont-email.me> <100vaoj$1d5lg$9@dont-email.me> <100ve0m$1e53o$1@dont-email.me> <10125hp$22da5$18@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Tue, 27 May 2025 10:29:41 +0200 (CEST) Injection-Info: dont-email.me; posting-host="4f458f81f94fb0e0c9ccea186385c32b"; logging-data="2671181"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+ndjEztV4H9Vi+xA6gd7sQ" User-Agent: Unison/2.2 Cancel-Lock: sha1:LQA5HHUrb6pdsVugTmMBamO3eMk= On 2025-05-26 16:40:25 +0000, olcott said: > On 5/25/2025 10:46 AM, Fred. Zwarts wrote: >> Op 25.mei.2025 om 16:50 schreef olcott: >>> On 5/25/2025 4:09 AM, Mikko wrote: >>>> On 2025-05-24 15:25:21 +0000, olcott said: >>>> >>>>> On 5/24/2025 2:54 AM, Mikko wrote: >>>>>> On 2025-05-23 16:04:49 +0000, olcott said: >>>>>> >>>>>>> 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. >>>>>> >>>>>> No, they don't. Some proofs derive the same conclusion with an essentially >>>>>> different approach. >>>>>> >>>>>> However, in spite of the differences, they do share a common fieature: >>>>>> your HHH is not a part of any of the proofs. >>>>> >>>>> All of the conventional proofs of the HP assume that >>>>> there is an *input D* that can actually do the opposite >>>>> of whatever value that HHH returns. >>>> >>>> Depends on what you mean by "conventional". If you merely mean proofs >>>> that apply ordinary logic then there are proofs with a different >>>> strategy. If you mean only proofs that use the same strategy that >>>> Turing used then you are closer to the truth. But there is no assumption >>>> about the exstence of such D. Its existence is proven. >>>> >>> >>> In seems that way until you pay much closer attention. >>> >>> int main() >>> { >>>    DDD(); // The HHH that DDD calls cannot report on the >>> }        // behavior of its caller because it cannot see >>>           // is caller. >>> >>> Even if HHH could see and report on the behavior of >>> its caller because its caller is not its input this >>> too is no good. >> >> It seems that way to you, until you pay somewhat closer attention. > > The HHH(DDD) must report on the behavior that its actual input > actually specified CANNOT BE VIOLATED. Of course it can. In fact HHH does violate that. DDD specifies a halting behaviour but HHH reports that DDD specifies a non-halting behaviour. That is a violation of that rquirement. -- Mikko