Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: Mikko Newsgroups: comp.theory Subject: Re: Anyone with sufficient knowledge of C knows that DD specifies non-terminating behavior to HHH Date: Wed, 19 Feb 2025 11:01:26 +0200 Organization: - Lines: 93 Message-ID: References: <3b8a5f4be53047b2a6c03f9678d0253e137d3c40@i2pn2.org> <5cd9bc55c484f10efd7818ecadf169a11fcc58e1@i2pn2.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 19 Feb 2025 10:01:28 +0100 (CET) Injection-Info: dont-email.me; posting-host="62a0c75673f890089d7b2c78b9ec8261"; logging-data="2321463"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19HVGW/WohwTP7ymiMguI6m" User-Agent: Unison/2.2 Cancel-Lock: sha1:Iz21OJYNGJIqxveWKZIeIsaproI= Bytes: 5514 On 2025-02-18 11:26:25 +0000, olcott said: > On 2/18/2025 3:24 AM, Mikko wrote: >> On 2025-02-17 09:05:42 +0000, Fred. Zwarts said: >> >>> Op 16.feb.2025 om 23:51 schreef olcott: >>>> On 2/16/2025 4:30 PM, joes wrote: >>>>> Am Sun, 16 Feb 2025 15:58:14 -0600 schrieb olcott: >>>>>> On 2/16/2025 2:02 PM, joes wrote: >>>>>>> Am Sun, 16 Feb 2025 13:24:14 -0600 schrieb olcott: >>>>>>>> On 2/16/2025 10:35 AM, joes wrote: >>>>>>>>> Am Sun, 16 Feb 2025 06:51:12 -0600 schrieb olcott: >>>>>>>>>> On 2/15/2025 2:49 AM, Mikko wrote: >>>>>>>>>>> On 2025-02-14 12:40:04 +0000, olcott said: >>>>>>>>>>>> On 2/14/2025 2:58 AM, Mikko wrote: >>>>>>>>>>>>> On 2025-02-14 00:07:23 +0000, olcott said: >>>>>>>>>>>>>> On 2/13/2025 3:20 AM, Mikko wrote: >>>>>>>>>>>>>>> On 2025-02-13 04:21:34 +0000, olcott said: >>>>>>>>>>>>>>>> On 2/12/2025 4:04 AM, Mikko wrote: >>>>>>>>>>>>>>>>> On 2025-02-11 14:41:38 +0000, olcott said: >>>>> >>>>>>>>>>>> DD  correctly simulated by HHH cannot possibly terminate normally. >>>>>>>>>>> >>>>>>>>>>> That claim has already shown to be false. Nothing above shows that >>>>>>>>>>> HHH does not return 0. If it does DD also returns 0. >>>>>>>>>> When we are referring to the above DD simulated by HHH and not >>>>>>>>>> trying to get away with changing the subject to some other DD >>>>>>>>>> somewhere else >>>>>>>>> such as one that calls a non-aborting version of HHH >>>>>>>>> >>>>>>>>>> then anyone with sufficient knowledge of C programming knows that no >>>>>>>>>> instance of DD shown above simulated by any corresponding instance >>>>>>>>>> of HHH can possibly terminate normally. >>>>>>>>> Well, then that corresponding (by what?) HHH isn’t a decider. >>>>>>>> I am focusing on the isomorphic notion of a termination analyzer. >>>>>>> (There are other deciders that are not termination analysers.) >>>>>>> >>>>>>>> A simulating termination analyzer correctly rejects any input that >>>>>>>> must be aborted to prevent its own non-termination. >>>>>>> Yes, in particular itself is not such an input, because we *know* that >>>>>>> it halts, because it is a decider. You can’t have your cake and eat it >>>>>>> too. >>>>>> I am not even using the confusing term "halts". >>>>>> Instead I am using in its place "terminates normally". >>>>>> DD correctly simulated by HHH cannot possibly terminate normally. >>>>> What’s confusing about „halts”? I find it clearer as it does not imply >>>>> an ambiguous „abnormal termination”. How does HHH simulate DD >>>>> terminating abnormally, then? Why doesn’t it terminate abnormally >>>>> itself? >>>>> You can substitute the term: the input DD to HHH does not need to be >>>>> aborted, because the simulated decider terminates. >>>>> >>>> >>>> typedef void (*ptr)(); >>>> int HHH(ptr P); >>>> >>>> int DD() >>>> { >>>>   int Halt_Status = HHH(DD); >>>>   if (Halt_Status) >>>>     HERE: goto HERE; >>>>   return Halt_Status; >>>> } >>>> >>>> int main() >>>> { >>>>   HHH(DD); >>>> } >>>> >>>> Every simulated input that must be aborted to >>>> prevent the non-termination of HHH is stipulated >>>> to be correctly rejected by HHH as non-terminating. >>>> >>> A very strange and invalid stipulation. >> >> It merely means that the words do not have their ordinary meaning. >> > > Unless HHH(DD) aborts its simulation of DD itself cannot possibly > terminate normally. That cannot be determined without examination of HHH, which is not in the scope of OP. > Every expert in the C programming language can see this. They can't when they can't see HHH and even then it is not obvious, so the claim on the subject line is false. -- Mikko