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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: Mikko Newsgroups: comp.theory Subject: Re: Overcoming the proof of undecidability of the Halting Problem by a simple example in C Date: Mon, 19 May 2025 12:36:17 +0300 Organization: - Lines: 54 Message-ID: <100eu2h$1i4s7$1@dont-email.me> References: <1005jsk$3akrk$1@dont-email.me> <1005u6v$3cpt2$1@dont-email.me> <1005v0p$3b07v$1@dont-email.me> <10063u0$3dmiv$1@dont-email.me> <1006on8$3l9t7$1@dont-email.me> <1007kgq$3qb7l$9@dont-email.me> <1009lm9$b15q$1@dont-email.me> <100ceum$uvq0$1@dont-email.me> <87ecwl1s2p.fsf@bsb.me.uk> <100dscu$18b5s$1@dont-email.me> <87v7pxzbp4.fsf@bsb.me.uk> <100du9m$18m8u$1@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Mon, 19 May 2025 11:36:18 +0200 (CEST) Injection-Info: dont-email.me; posting-host="8f4381c44869abbb66b062db77a9c084"; logging-data="1643399"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/JSWzQ9gb5o/sQkdYYe0B1" User-Agent: Unison/2.2 Cancel-Lock: sha1:EIbSsJpOmxJqm5vc7AfDezHoTRo= On 2025-05-19 00:33:58 +0000, olcott said: > On 5/18/2025 7:27 PM, Ben Bacarisse wrote: >> Richard Heathfield writes: >> >>> On 18/05/2025 23:18, Ben Bacarisse wrote: >>>> Richard Heathfield writes: >>>> ... >>>>> If they know C they should know that it's >>>>> u32 HHH(void (*P)()), according to Halt7.c. >>>>> >>>>> It takes a pointer to a function that accepts no arguments and returns no >>>>> value. >>>> Yes, but I am surprised that you are being so modern!! You used to >>>> favour C90 and didn't really care for anything more recent. >>> >>> I am just as surprised that you missed the distinction I was making, which >>> was between these: >>> >>> void HHH(void (*f)(void)) >>> u32 HHH(void (*P)()) >>> >>> Empty parentheses had nothing to do with my point. On line 16 we find: >>> typedef uint32_t u32; >>> >>> uint32_t != void. >> >> Yes, I got the distinction you were making, but I must have got confused >> about the referent of "it" in the part I quoted. I was hoping to add >> to the discussion despite ignoring your main point. Sorry. >> > > *Copied from the original post that he responded to* > > int DD() > { > int Halt_Status = HHH(DD); > if (Halt_Status) > HERE: goto HERE; > return Halt_Status; > } > > HHH simulates DD that calls HHH(DD) to simulate itself > again over and over until HHH sees this repeating pattern > and aborts or both HHH and DD crash due to OOM error. > > His main point was to dodge the actual meaning > of the word *simulate* Whose? -- Mikko