Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Mikko <mikko.levanto@iki.fi>
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> <bc6f0f045212bdfb7f7d883426873a09e37789ea@i2pn2.org> <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 <rjh@cpax.org.uk> writes:
>> 
>>> On 18/05/2025 23:18, Ben Bacarisse wrote:
>>>> Richard Heathfield <rjh@cpax.org.uk> 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