Path: 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 12:41:11 +0300 Organization: - Lines: 68 Message-ID: <100eubn$1i76n$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> <100dvuj$18b5q$2@dont-email.me> <100e17m$194d7$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 11:41:12 +0200 (CEST) Injection-Info: dont-email.me; posting-host="8f4381c44869abbb66b062db77a9c084"; logging-data="1645783"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18nMSAQBoD4s0ExBSjcttIg" User-Agent: Unison/2.2 Cancel-Lock: sha1:RPVer5GjByT1nrqPJKApVxnz0l8= On 2025-05-19 01:24:06 +0000, olcott said: > On 5/18/2025 8:02 PM, Richard Heathfield wrote: >> On 19/05/2025 01:33, olcott wrote: >>> On 5/18/2025 7:27 PM, Ben Bacarisse wrote: >>>> Richard Heathfield writes: >> >> [Apologies for not snipping. This one was hard to know how best to edit down.] >> >>>> >>>>> 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; >>>   } >> >> Not so. The post I responded to was Message-ID: <1009lm9$b15q$1@dont- email.me> >> >> There was a lot of quoted material, none of which mentioned int DD(), >> although it did mention a void DDD(). >> >> The only original material was: >> >> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> No, there are peole who do know C but don't know that HHH is not >> void HHH(void (*f)(void)) {} and how therefore cannot tell that >> HHH does simulate DDD. > > It was stipulated that HHH does simulate DDD. > No need to check every little punctuation mark. Not in the message about what people who know C know. There are people who know C but not your stipulations. -- Mikko