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 11:31:37 +0300 Organization: - Lines: 134 Message-ID: <1013t99$2hhmd$1@dont-email.me> References: <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> <10119a9$1tver$1@dont-email.me> <10122jj$22da5$7@dont-email.me> <10123fp$22udp$2@dont-email.me> <10124o8$22da5$17@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 10:31:37 +0200 (CEST) Injection-Info: dont-email.me; posting-host="4f458f81f94fb0e0c9ccea186385c32b"; logging-data="2672333"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/k9u/2ahctR2PqfL6xcU28" User-Agent: Unison/2.2 Cancel-Lock: sha1:Xys2NtyCMaxayqmwkPcICOy3GrY= On 2025-05-26 16:26:47 +0000, olcott said: > On 5/26/2025 11:05 AM, Fred. Zwarts wrote: >> Op 26.mei.2025 om 17:50 schreef olcott: >>> On 5/26/2025 3:38 AM, Mikko wrote: >>>> On 2025-05-25 14:50:58 +0000, olcott said: >>>> >>>>> 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. >>>> >>>> No, it seems that way when you pay enough attention. >>>> >>>>> int main() >>>>> { >>>>>    DDD(); // The HHH that DDD calls cannot report on the >>>>> }        // behavior of its caller because it cannot see >>>>>           // is caller. >>>> >>>> If HHH is correctly constructed it does see DDD and everything DDD >>>> calls. Nothing else is relevant. >>>> >>> >>> Try to show how HHH can see anything about its own caller >>> when HHH is not even allowed to look at its caller. >>> >> >> It is irrelevant whether DDD is the caller of HHH or not. >> int main() >>  { >>     HHH(DDD); >>     return; >>  } >> >> Now HHH is not called from HHH, but has the same input and it should >> see that DDD includes the Halt7.c code, which aborts, so it should see: >> a halting program. > > In other words you fail to understand that > halting requires reaching a final halt state. It is a sin to present false claims about tother peoples understanding. -- Mikko