Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: olcott Newsgroups: comp.lang.c++,comp.lang.c Subject: Re: D correctly simulated by pure function H remains stuck in recursive simulation Date: Wed, 22 May 2024 16:45:13 -0500 Organization: A noiseless patient Spider Lines: 59 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 22 May 2024 23:45:13 +0200 (CEST) Injection-Info: dont-email.me; posting-host="9557ecc38a2c6e613b1947df9dd7fc56"; logging-data="1448243"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18BVL3QWUhT3LIIPKE6NXH+" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:TlBZCLACol4jSBu3RPR7qRNN+YM= In-Reply-To: Content-Language: en-US Bytes: 3353 On 5/22/2024 3:09 PM, Bonita Montero wrote: > Am 22.05.2024 um 21:57 schrieb olcott: >> On 5/22/2024 11:31 AM, Bonita Montero wrote: >>> Am 22.05.2024 um 15:57 schrieb olcott: >>>> Because D correctly simulated by pure function H remains stuck in >>>> recursive simulation simulating termination analyzer H is correct >>>> to report that D does not halt. >>>> >>>> typedef int (*ptr)();  // ptr is pointer to int function in C >>>> 00       int H(ptr p, ptr i); >>>> 01       int D(ptr p) >>>> 02       { >>>> 03         int Halt_Status = H(p, p); >>>> 04         if (Halt_Status) >>>> 05           HERE: goto HERE; >>>> 06         return Halt_Status; >>>> 07       } >>>> 08 >>>> 09       int main() >>>> 10       { >>>> 11         H(D,D); >>>> 12         return 0; >>>> 13       } >>>> >>>> It is trivial to see that for every H/D pair of the infinite >>>> set of H/D pairs that match the above template that >>>> >>>> D correctly simulated by H cannot possibly reach its own final >>>> state at line 06 and halt because D correctly simulated by >>>> H remains stuck in recursive simulation. >>>> >>>> This provides the basis for simulating termination analyzer H to >>>> correctly determine that the halting problem's counter-example >>>> input D cannot possibly halt. >>>> >>> >>> Ok, then every question is answered and we could proceed to >>> "sth. completely different" (Monty Python). >>> >> >> *No this question has never been answered in this forum* >> > > Because this question is about C++ and not theoretical computer > sciences. My question is ONLY about the semantics of the above c17 code and what behavior that this semantics entails. I don't want or need any answer outside of this scope in this forum. The people in other forums have proven to be incompetent about the behavior specified by the above c17 code. -- Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer