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Path: ...!news.nobody.at!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: "Fred. Zwarts" <F.Zwarts@HetNet.nl> Newsgroups: comp.theory Subject: Re: Proof that DDD specifies non-halting behavior --- Mike correcting Joes Date: Thu, 15 Aug 2024 17:40:30 +0200 Organization: A noiseless patient Spider Lines: 47 Message-ID: <v9l7hf$vao1$3@dont-email.me> References: <v9gv4k$4sc4$1@dont-email.me> <561f876601b0329c0260bac26f8b6dfb6e28647f@i2pn2.org> <v9h5af$9jn6$1@dont-email.me> <bdfcf881b9a9ce7e2bc197339d14a01beae1116d@i2pn2.org> <XYucnXqdgeWiVSH7nZ2dnZfqn_adnZ2d@brightview.co.uk> <b8a96bbfe0516cf99b6f38c23fb4eccc3810ee7e@i2pn2.org> <v9krc5$uqhs$1@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Thu, 15 Aug 2024 17:40:32 +0200 (CEST) Injection-Info: dont-email.me; posting-host="6fe5c52353619c0eaa47b74070d55905"; logging-data="1026817"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18y4Iv5os7WziQIermxLOnn" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:f7hnRMOixKxl7rq3RpE7Gm0bE6E= Content-Language: en-GB In-Reply-To: <v9krc5$uqhs$1@dont-email.me> Bytes: 3323 Op 15.aug.2024 om 14:12 schreef olcott: > On 8/15/2024 2:00 AM, joes wrote: >> Am Wed, 14 Aug 2024 16:07:43 +0100 schrieb Mike Terry: >>> On 14/08/2024 08:43, joes wrote: >>>> Am Tue, 13 Aug 2024 21:38:07 -0500 schrieb olcott: >>>>> On 8/13/2024 9:29 PM, Richard Damon wrote: >>>>>> On 8/13/24 8:52 PM, olcott wrote: >>>> >>>>>>> A simulation of N instructions of DDD by HHH according to the >>>>>>> semantics of the x86 language is necessarily correct. >>>>>> Nope, it is just the correct PARTIAL emulation of the first N >>>>>> instructions of DDD, and not of all of DDD, >>>>> That is what I said dufuss. >>>> You were trying to label an incomplete/partial/aborted simulation as >>>> correct. >>>> >>>>>>> A correct simulation of N instructions of DDD by HHH is sufficient >>>>>>> to correctly predict the behavior of an unlimited simulation. >>>>>> Nope, if a HHH returns to its caller, >>>>> *Try to show exactly how DDD emulated by HHH returns to its caller* >>>> how *HHH* returns >> >>>> HHH simulates DDD enter the matrix >>>> DDD calls HHH(DDD) Fred: could be eliminated HHH simulates >> DDD >>>> second level >>>> DDD calls HHH(DDD) recursion detected >>>> HHH aborts, returns outside interference DDD halts >> voila >>>> HHH halts >>> >>> You're misunderstanding the scenario? If your simulated HHH aborts its >>> simulation [line 5 above], >>> then the outer level H would have aborted its identical simulation >>> earlier. You know that, right? > >> Of course. I made it only to illustrate one step in the paradoxical >> reasoning, as long as we're calling programs that do or don't abort >> the same. >> > > It is like I always pointed out. The outer HHH cannot > wait for the inner ones to abort because it would be > waiting forever. Exactly. And when it aborts, it aborts too soon, one cycle before the simulated HHH would abort and halt. HHH cannot possibly simulate itself correctly.