Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: "Fred. Zwarts" Newsgroups: comp.theory Subject: Re: Incorrect requirements --- Computing the mapping from the input to HHH(DD) Date: Fri, 9 May 2025 11:00:22 +0200 Organization: A noiseless patient Spider Lines: 56 Message-ID: References: <87msbmeo3b.fsf@nosuchdomain.example.com> <875xiaejzg.fsf@nosuchdomain.example.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 09 May 2025 11:00:23 +0200 (CEST) Injection-Info: dont-email.me; posting-host="effaaa99691bef49d0e396f91c654de7"; logging-data="2821341"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+gvrWCCZaiwAB920bvhlLQ" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:RxqAQ4WPZNdEXaAfisdXEvBR5Wg= In-Reply-To: Content-Language: nl, en-GB Op 09.mei.2025 om 02:05 schreef olcott: > On 5/8/2025 6:54 PM, Keith Thompson wrote: >> olcott writes: >>> On 5/8/2025 6:30 PM, Richard Heathfield wrote: >>>> On 08/05/2025 23:50, olcott wrote: >> [...] >>>>> If you are a competent C programmer >>>> Keith Thompson is a highly-respected and very competent C >>>> programmer. >>> >>> *Then he is just who I need* >> >> No, what you need is someone who is an expert in mathematical logic >> (I am not) who can explain to you, in terms you can understand and >> accept, where you've gone wrong.  Some expertise in C could also >> be helpful. >> > > The key gap in my proof is that none of the comp.sci > people seems to have a slight clue about simple C > programming. > > void DDD() > { >   HHH(DDD); >   return; > } > > *THIS IS THE C PART THAT NO ONE HERE UNDERSTANDS* > DDD correctly simulated by HHH cannot possibly > reach its own "return" instruction. The HHH that you propose and is included in DDD does halt. But it is known that this HHH prematurely aborts which makes it impossible for the simulation to reach the reachable 'return'. HHH simply ignores the conditional abort in the simulation. The hypothetical HHH, that does not abort would reach the 'return' when given the same input. We could also construct another hypothetical DDD based on this hypothetical HHH, but then the simulation would get stuck in infinite recursion. But since those hypothetical functions only exist in your dreams, they are irrelevant for the discussion about the HHH that your propose, which aborts. > > DDD correctly simulated by HHH is the same thing > as infinite recursion between HHH and DDD yet is > implemented as recursive simulation. That is true in your dreams of the non-aborting HHH. In reality there is a HHH that aborts, so there is only a finite recursion. I am sorry for you that the truth disturbs your dreams.