Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Richard Heathfield <rjh@cpax.org.uk>
Newsgroups: comp.theory
Subject: Re: Overcoming the proof of undecidability of the Halting Problem by
 a simple example in C
Date: Fri, 16 May 2025 16:48:56 +0100
Organization: Fix this later
Lines: 36
Message-ID: <1007mp8$3r37u$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>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Injection-Date: Fri, 16 May 2025 17:48:57 +0200 (CEST)
Injection-Info: dont-email.me; posting-host="c9b5d4175918213114d05d0efe3ca7b3";
	logging-data="4033790"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+CWuPJQQgPqXL/uTuXk7AHsTj/gyzWcOqa3yW7sZeuMQ=="
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:SxiUMeqrzdD/Me5CDKfjM4Qlix8=
In-Reply-To: <1007kgq$3qb7l$9@dont-email.me>
Content-Language: en-GB

On 16/05/2025 16:10, olcott wrote:

<snip>

> 
> void DDD()
> {
>    HHH(DDD);
>    return;
> }
> 
> Anyone that knows C can tell that when HHH does simulate
> DDD correctly that it keeps getting deeper in recursive
> simulation until aborted or OOM error.

Anyone who knows C knows that there isn't much HHH can do with 
the pointer value it's given. It can call DDD:

(*p)();

or it can pass its value to another function, or it can store its 
value in an object of the appropriate type.

That's it. Anything else it does with it leaves the rules of C 
far behind. C won't stop you playing the games you want to play, 
but you are no longer playing C.

So anyone that knows C can tell that the rules of C don't work 
the way you want them too.

-- 
Richard Heathfield
Email: rjh at cpax dot org dot uk
"Usenet is a strange place" - dmr 29 July 1999
Sig line 4 vacant - apply within