Path: news.eternal-september.org!eternal-september.org!feeder3.eternal-september.org!news.quux.org!news.nk.ca!rocksolid2!i2pn2.org!.POSTED!not-for-mail From: Richard Damon Newsgroups: comp.theory Subject: Re: How do computations actually work? Date: Thu, 29 May 2025 07:04:08 -0400 Organization: i2pn2 (i2pn.org) Message-ID: <4964e41f087167958cab58d6fef6c4991ba4ed8e@i2pn2.org> References: <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> <1013t5k$2hgid$1@dont-email.me> <1014mdi$2lsi8$8@dont-email.me> <1016ee6$352ij$1@dont-email.me> <10176n6$39etk$1@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Thu, 29 May 2025 11:29:14 -0000 (UTC) Injection-Info: i2pn2.org; logging-data="2409768"; mail-complaints-to="usenet@i2pn2.org"; posting-account="diqKR1lalukngNWEqoq9/uFtbkm5U+w3w6FQ0yesrXg"; User-Agent: Mozilla Thunderbird X-Spam-Checker-Version: SpamAssassin 4.0.0 In-Reply-To: <10176n6$39etk$1@dont-email.me> Content-Language: en-US On 5/28/25 10:31 AM, olcott wrote: > On 5/28/2025 2:36 AM, Mikko wrote: >> On 2025-05-27 15:40:33 +0000, olcott said: >> >>> On 5/27/2025 3:29 AM, Mikko wrote: >>>> 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. >>> >>> If DDD simulated by HHH stops running for any >>> reason besides reaching its own "ret" instruction >>> final halt state THEN DDD HAS NOT HALTED. >> >> Irrelevant. The requirement is that a halt decider predicts whether the >> complete execution of the computation described by the input will halt. >> > > Halting is defined as reaching a final state and > terminating normally. In the behavior of the actual program. And Non-Halting is thus defined as will never reach a final state after an unbounded number of steps. > > int main() > { >   DDD(); // The HHH that DDD calls cannot > }        // see the behavior of its caller > That it can not see is irrelevent, it *IS* the behavior it is being asked to determine. Lying is not a valid option in logic. > *That is incorrect* > A termination analyzer must report on the basis > of the behavior that its input specifies and does ========== REMAINDER OF ARTICLE TRUNCATED ==========