Path: ...!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.theory Subject: Re: Who here understands that the last paragraph is Necessarily true? Date: Sat, 20 Jul 2024 09:49:28 -0500 Organization: A noiseless patient Spider Lines: 173 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Sat, 20 Jul 2024 16:49:29 +0200 (CEST) Injection-Info: dont-email.me; posting-host="c302f5257903c7c25aa8d1f6976e7879"; logging-data="3766309"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18p+T5pkVaqM3SKWJ7ZT7jS" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:EJgM03W5KUjn7ouNiL7bgJHJ5Hg= Content-Language: en-US In-Reply-To: Bytes: 7718 On 7/20/2024 4:30 AM, Mikko wrote: > On 2024-07-19 14:46:19 +0000, olcott said: > >> On 7/19/2024 4:07 AM, Mikko wrote: >>> On 2024-07-17 13:30:07 +0000, olcott said: >>> >>>> On 7/17/2024 2:49 AM, Mikko wrote: >>>>> On 2024-07-16 14:20:09 +0000, olcott said: >>>>> >>>>>> On 7/16/2024 3:32 AM, Mikko wrote: >>>>>>> On 2024-07-15 13:26:22 +0000, olcott said: >>>>>>> >>>>>>>> On 7/15/2024 3:23 AM, Mikko wrote: >>>>>>>>> On 2024-07-14 14:38:31 +0000, olcott said: >>>>>>>>> >>>>>>>>>> On 7/14/2024 3:09 AM, Mikko wrote: >>>>>>>>>>> On 2024-07-13 20:15:56 +0000, olcott said: >>>>>>>>>>> >>>>>>>>>>>> typedef void (*ptr)(); >>>>>>>>>>>> int HHH(ptr P); >>>>>>>>>>>> >>>>>>>>>>>> void Infinite_Loop() >>>>>>>>>>>> { >>>>>>>>>>>>    HERE: goto HERE; >>>>>>>>>>>> } >>>>>>>>>>>> >>>>>>>>>>>> void Infinite_Recursion() >>>>>>>>>>>> { >>>>>>>>>>>>    Infinite_Recursion(); >>>>>>>>>>>> } >>>>>>>>>>>> >>>>>>>>>>>> void DDD() >>>>>>>>>>>> { >>>>>>>>>>>>    HHH(DDD); >>>>>>>>>>>> } >>>>>>>>>>>> >>>>>>>>>>>> int main() >>>>>>>>>>>> { >>>>>>>>>>>>    HHH(Infinite_Loop); >>>>>>>>>>>>    HHH(Infinite_Recursion); >>>>>>>>>>>>    HHH(DDD); >>>>>>>>>>>> } >>>>>>>>>>>> >>>>>>>>>>>> Any input that must be aborted to prevent the non >>>>>>>>>>>> termination of HHH necessarily specifies non-halting >>>>>>>>>>>> behavior or it would never need to be aborted. >>>>>>>>>>> >>>>>>>>>>> Everyone understands that DDD specifies a halting behaviour >>>>>>>>>>> if HHH(DDD) does, >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> *You can comprehend this is a truism or fail to* >>>>>>>>>> *comprehend it disagreement is necessarily incorrect* >>>>>>>>>> Any input that must be aborted to prevent the non >>>>>>>>>> termination of HHH necessarily specifies non-halting >>>>>>>>>> behavior or it would never need to be aborted. >>>>>>>>>> >>>>>>>>>> Disagreeing with the above is analogous to disagreeing >>>>>>>>>> with arithmetic. >>>>>>>>> >>>>>>>>> That the input is aborted does not mean that the input must be >>>>>>>>> aborted. >>>>>>>> >>>>>>>> Weasel words. This is an axiom: >>>>>>>> Input XXX must be aborted to prevent the non-termination of HHH. >>>>>>> >>>>>>> That is not an acceptable axiom. That you are unable to prove that >>>>>>> either XXX is aborted or HHH does not terminate is insufficient >>>>>>> reason to call it an axiom. >>>>>>> >>>>>> >>>>>> *Premise* (assumed to be true) >>>>>> Any input that must be aborted to prevent >>>>>> the non termination of HHH >>>>>> >>>>>> *Logically entailed by the above premise* >>>>>> necessarily specifies non-halting behavior or >>>>>> it would never need to be aborted. >>>>> >>>>> No, it is not. Both "need to be" and "must be" are different from >>>>> "is". >>>>> The correct asxiom is "If the program can be executed to its >>>>> halting in >>>>> a finite time then the program specifies a halting behaviour." >>>>> >>>>>>>> From the fact that XXX must be aborted we can conclude that XXX >>>>>>>> must be aborted. >>>>>>> >>>>>>> Nothing that contains the word "must" is a fact. >>>>>>> >>>>>> >>>>>> When simulated input X stops running {if and only if} >>>>>> the simulation of this input X has been aborted this >>>>>> necessitates that input X specifies non-halting behavior. >>>>> >>>>> Nothing that contains the word "necessitates" is a fact, either. >>>>> Perhaps you should learn some philosophy. >>>>> >>>> >>>> >>>>      If simulating halt decider H correctly simulates its input D >>>>      until H correctly determines that its simulated D would never >>>>      stop running unless aborted then >>>> >>>>      H can abort its simulation of D and correctly report that D >>>>      specifies a non-halting sequence of configurations. >>>> >>>> >>>> _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] >>>> >>>> DDD emulated by HHH according to the semantic meaning of >>>> its x86 instructions never stops running unless aborted. >>> >>> That Professor Sipser does not express any agreement with anything >>> about the syntax of facts is not relevant to our (or any) discussion >>> about syntax of facts. >>> >> >> void DDD() >> { >>    HHH(DDD); >> } >> >> int main() >> { >>    DDD(); >> } >> >> >>      If simulating halt decider H correctly simulates its input D >>      until H correctly determines that its simulated D would never >>      stop running unless aborted then >> >>      H can abort its simulation of D and correctly report that D >>      specifies a non-halting sequence of configurations. >> >> >> int main { DDD(); } calls HHH(DDD) that must abort the >> emulation of its input or HHH, emulated DDD and executed DDD >> never stop running. > > If HHH can detect that a part of the code to be emulated ie HHH itself it > may skip the emulation of itself and continue from the return. The > knowledge > that HHH always terminates can be coded in HHH. Therefore the abortion is > not necessary. > In other words you are suggesting that HHH lies and makes pretend that recursive emulation does not exist. _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] -- Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer