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Failed to connect to MySQL: (1203) User howardkn already has more than 'max_user_connections' active connectionsPath: ...!2.eu.feeder.erje.net!3.eu.feeder.erje.net!feeder.erje.net!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: Can you see that D correctly simulated by H remains stuck in recursive simulation? Date: Fri, 24 May 2024 08:08:52 -0500 Organization: A noiseless patient Spider Lines: 62 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 24 May 2024 15:08:52 +0200 (CEST) Injection-Info: dont-email.me; posting-host="853a48eea7a3e841565c364baea8e5bf"; logging-data="2461171"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/9lFKKafJN7EIFGmZKuVH4" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:lkpdmrDO1fI4PoLDxsnZZyOTWIk= Content-Language: en-US In-Reply-To: Bytes: 3308 On 5/24/2024 7:10 AM, Richard Harnden wrote: > On 23/05/2024 17:52, olcott wrote: >> 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       } >> >> The above template refers to an infinite set of H/D pairs where D is >> correctly simulated by pure function H. This was done because many >> reviewers used the shell game ploy to endlessly switch which H/D was >> being referred to. >> >> *Correct Simulation Defined* >> This is provided because every reviewer had a different notion of >> correct simulation that diverges from this notion. >> >> In the above case a simulator is an x86 emulator that correctly emulates >> at least one of the x86 instructions of D in the order specified by the >> x86 instructions of D. >> >> This may include correctly emulating the x86 instructions of H in the >> order specified by the x86 instructions of H thus calling H(D,D) in >> recursive simulation. >> >> *Execution Trace* >> Line 11: main() invokes H(D,D); H(D,D) simulates lines 01, 02, and 03 of >> D. This invokes H(D,D) again to repeat the process in endless recursive >> simulation. > > > So, you have: main -> H -> D -> H -> D -> ... -> H -> D until you run > out of stack? > > No return statement is ever reached. > Line 3 never completes. > Halt_Status at line 3 never gets a value. > > > > Thanks. Proving that D correctly simulated by H never reaches its final state at line 06 and halts. Thus proving that the halting problem's counter-example input D would be correctly determined to be non-halting by its simulating termination analyzer H. -- Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer