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Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Mikko <mikko.levanto@iki.fi> Newsgroups: comp.theory Subject: Re: DDD correctly emulated by HHH is correctly rejected as non-halting V2 Date: Wed, 17 Jul 2024 09:52:46 +0300 Organization: - Lines: 67 Message-ID: <v77pnu$1nn5l$2@dont-email.me> References: <v6rg65$32o1o$3@dont-email.me> <v7085g$3j1h$1@dont-email.me> <v70ok7$61d8$10@dont-email.me> <v72lvl$k9t3$1@dont-email.me> <v73926$mjis$17@dont-email.me> <v75950$166e9$1@dont-email.me> <v76dgv$1cf96$2@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 17 Jul 2024 08:52:46 +0200 (CEST) Injection-Info: dont-email.me; posting-host="65978254551784bf68c380dad1a46784"; logging-data="1825973"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+PzUsmKYNbZCvGGRNAInsV" User-Agent: Unison/2.2 Cancel-Lock: sha1:Gt8qLL4phWiRKBncMlXOp6CfiNo= Bytes: 3734 On 2024-07-16 18:18:07 +0000, olcott said: > On 7/16/2024 2:57 AM, Mikko wrote: >> On 2024-07-15 13:43:34 +0000, olcott said: >> >>> On 7/15/2024 3:17 AM, Mikko wrote: >>>> On 2024-07-14 14:50:47 +0000, olcott said: >>>> >>>>> On 7/14/2024 5:09 AM, Mikko wrote: >>>>>> On 2024-07-12 14:56:05 +0000, olcott said: >>>>>> >>>>>>> We stipulate that the only measure of a correct emulation is the >>>>>>> semantics of the x86 programming language. >>>>>>> >>>>>>> _DDD() >>>>>>> [00002163] 55 push ebp ; housekeeping >>>>>>> [00002164] 8bec mov ebp,esp ; housekeeping >>>>>>> [00002166] 6863210000 push 00002163 ; push DDD >>>>>>> [0000216b] e853f4ffff call 000015c3 ; call HHH(DDD) >>>>>>> [00002170] 83c404 add esp,+04 >>>>>>> [00002173] 5d pop ebp >>>>>>> [00002174] c3 ret >>>>>>> Size in bytes:(0018) [00002174] >>>>>>> >>>>>>> When N steps of DDD are emulated by HHH according to the >>>>>>> semantics of the x86 language then N steps are emulated correctly. >>>>>>> >>>>>>> When we examine the infinite set of every HHH/DDD pair such that: >>>>>>> HHH₁ one step of DDD is correctly emulated by HHH. >>>>>>> HHH₂ two steps of DDD are correctly emulated by HHH. >>>>>>> HHH₃ three steps of DDD are correctly emulated by HHH. >>>>>>> ... >>>>>>> HHH∞ The emulation of DDD by HHH never stops running. >>>>>>> >>>>>>> The above specifies the infinite set of every HHH/DDD pair >>>>>>> where 1 to infinity steps of DDD are correctly emulated by HHH. >>>>>> >>>>>> You should use the indices here, too, e.g., "where 1 to infinity steps of >>>>>> DDD₁ are correctly emulated by HHH₃" or whatever you mean. >>>>>> >>>>> >>>>> DDD is the exact same fixed constant finite string that >>>>> always calls HHH at the same fixed constant machine >>>>> address. >>>> >>>> If the function called by DDD is not part of the input then the input does >>>> not specify a behaviour and the question whether DDD halts is ill-posed. >>>> >>> >>> We don't care about whether HHH halts. We know that >>> HHH halts or fails to meet its design spec. >>> >>> We are only seeing if DDD correctly emulated by HHH >>> can can possibly reach its own final state. >> >> HHH does not see even that. It only sees whther that it does not emulate >> DDD to its final state. > > No. HHH is not judging whether or not itself is a correct > emulator. The semantics of the x86 instructions that emulates > prove that its emulation is correct. The semantics does not prove. Only a proof would prove. -- Mikko