Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: olcott Newsgroups: comp.theory Subject: Re: Every D(D) simulated by H presents non-halting behavior to H ### Date: Tue, 14 May 2024 09:35:42 -0500 Organization: A noiseless patient Spider Lines: 86 Message-ID: References: <-5Gdnf-nQvstC6b7nZ2dnZfqnPadnZ2d@brightview.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Tue, 14 May 2024 16:35:43 +0200 (CEST) Injection-Info: dont-email.me; posting-host="e9b15de5cbd4b611ca4438a3f5fabf94"; logging-data="244556"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19iTJViDYd69MYx0SFmNmPA" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:h8jaZ0JJgZe//543Ssq8q0ZoJI4= In-Reply-To: Content-Language: en-US Bytes: 4191 On 5/14/2024 4:52 AM, Mikko wrote: > On 2024-05-13 14:43:09 +0000, olcott said: > >> On 5/13/2024 4:14 AM, Mikko wrote: >>> On 2024-05-13 04:54:30 +0000, immibis said: >>> >>>> On 10/05/24 19:55, Alan Mackenzie wrote: >>>>> [ Followup-To: set ] >>>>> >>>>> In comp.theory olcott wrote: >>>>> >>>>> [ .... ] >>>>> >>>>> I've tried out your much spammed code on GCC (see below).  It is clear >>>>> you have never built or run this code, which ironically can't reach >>>>> Line >>>>> 06.  It can't even reach line 00. >>>>> >>>>>> Richard tried to get away with D never simulated by H as an example >>>>>> of D simulated by H: >>>>> >>>>>> Message-ID: >>>>>> On 5/1/2024 7:28 PM, Richard Damon wrote: >>>>> >>>>>> *That people say they know I am wrong yet will not show the detailed* >>>>>> *steps of how I am wrong indicates that they are probably liars* >>>>> >>>>> You have said, or at least implied that your code fragment is >>>>> runnable. >>>>> I think you are the liar, here. >>>>> >>>>>> 00 int H(ptr x, ptr x)  // ptr is pointer to int function >>>>>> 01 int D(ptr x) >>>>>> 02 { >>>>>> 03   int Halt_Status = H(x, x); >>>>>> 04   if (Halt_Status) >>>>>> 05     HERE: goto HERE; >>>>>> 06   return Halt_Status; >>>>>> 07 } >>>>>> 08 >>>>>> 09 int main() >>>>>> 10 { >>>>>> 11   H(D,D); >>>>>> 12 } >>>>> >>>>> >>>>> .  These are the diagnostics generated by GCC: >>>>> >>>> And the halting problem is about Turing machines, anyway. >>> >>> Not necessarily. The same question can be asked about different >>> machines. >>> The restriction to Turing machines is just one way to ensure that the >>> problem is well defined. >>> >> >> Well put. All computable functions even if written in C. > > You still must ensure that the problem is well defined. With C there is > the problem that conforming C programs often fail to be strictly > conforming. > If a program is not strictly conforming it may be interpreted as halting > by some implementation and non-halting or incorrect by another. > 00 int H(ptr x, ptr x) // ptr is pointer to int function 01 int D(ptr x) 02 { 03 int Halt_Status = H(x, x); 04 if (Halt_Status) 05 HERE: goto HERE; 06 return Halt_Status; 07 } 08 09 int main() 10 { 11 H(D,D); 12 } One can correctly determine that every D simulated by H never reaches past its own line 03. -- Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer