Path: ...!news.mixmin.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: olcott Newsgroups: comp.theory Subject: Re: Can D simulated by H terminate normally? Date: Sat, 4 May 2024 08:56:27 -0500 Organization: A noiseless patient Spider Lines: 126 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Sat, 04 May 2024 15:56:28 +0200 (CEST) Injection-Info: dont-email.me; posting-host="2d5b94937ab75d91202558453b5391e6"; logging-data="1309425"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/Rx7/lb77G+/09bIgCByJh" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:otqnmToj0ZL2nGAzloIQz3CEAjk= Content-Language: en-US In-Reply-To: Bytes: 6042 On 5/4/2024 4:47 AM, Mikko wrote: > On 2024-05-03 11:55:15 +0000, olcott said: > >> On 5/3/2024 4:33 AM, Mikko wrote: >>> On 2024-05-02 18:35:19 +0000, olcott said: >>> >>>> On 5/2/2024 4:39 AM, Alan Mackenzie wrote: >>>>> olcott wrote: >>>>>> On 4/30/2024 5:46 PM, Richard Damon wrote: >>>>>>> On 4/30/24 12:15 PM, olcott wrote: >>>>>>>> On 4/30/2024 10:44 AM, Alan Mackenzie wrote: >>>>>>>>> olcott wrote: >>>>>>>>>> On 4/30/2024 3:46 AM, Fred. Zwarts wrote: >>>>>>>>>>> Op 29.apr.2024 om 21:04 schreef olcott: >>>>> >>>>> [ .... ] >>>>> >>>>>>>> When we add the brand new idea of {simulating termination >>>>>>>> analyzer} to >>>>>>>> the existing idea of TM's then we must be careful how we define >>>>>>>> halting >>>>>>>> otherwise every infinite loop will be construed as halting. >>>>> >>>>> >>>>>>> Why? >>>>> >>>>>>> That doesn't mean the machine reached a final state. >>>>> >>>>> >>>>>> Alan seems to believe that a final state is whatever state that an >>>>>> aborted simulation ends up in. >>>>> >>>>> Only through your twisted reasoning.  For your information, I hold >>>>> to the >>>>> standard definition of final state, i.e. one which has no state >>>>> following >>>>> it.  An aborted simulation is in some state, and that state is a final >>>>> one, since there is none following it. >>>>> >>>>>> On 4/30/2024 10:44 AM, Alan Mackenzie wrote: >>>>>>> You are thus mistaken in believing "abnormal" termination >>>>>>> isn't a final state. >>>>> >>>>>>> Only if you try to define something that is NOT related to >>>>>>> Halting, do >>>>>>> you get into that issue. >>>>> >>>>>> "The all new ideas are wrong" assessment. >>>>>> Simulating termination analyzers related to halting. >>>>> >>>>> Except you cannot define what such a thing is, and that >>>>> relationship is >>>>> anything but clear. >>>> >>>> When a simulating termination analyzer matches one of three >>>> non-halting behavior patterns >>>> (a) Simple Infinite loop >>>> (b) Simple Infinite Recursion >>>> (c) Simple Recursive Simulation >>> >>> Simple recursive simulation is not a non-halting behaviour >>> if the recursion is not infinite. >> >> In other words the only way that we can tell that an infinite >> loop never halts is to simulate it until the end of time? > > The phrase "in other words" is not correct here as it means that > what follows means the same as what precedes, and that is not > true here. > > For same loops the only wha to detect non-termination may be > to simulate to infinity but they can be considered exluded by > the term "simple" in (a). > >> There are repeating state non-halting behavior patterns >> that can be recognized. These are three more functions >> where H derives the correct halt status: >> >> void Infinite_Recursion(u32 N) >> { >>    Infinite_Recursion(N); >> } > > Per (b) that is non-halting and indeed it is (though the > execution may crash for "out of memeory"). > It is not actually infinite though because H recognizes the non-halting behavior pattern, aborts the simulation and reports non-halting. It is the exact same thing with D simulated by H on the basis of the directly executed H(D,D). >> void Infinite_Loop() >> { >>    HERE: goto HERE; >> } > > Per (a) that is non-halting and indeed it is. It is not actually infinite though because H recognizes the non-halting behavior pattern, aborts the simulation and reports non-halting. It is the exact same thing with D simulated by H on the basis of the directly executed H(D,D). > >> int factorial(int n) >> { >>    if (n >= 1) >>      return n*factorial(n-1); >>    else >>      return 1; >> } > > Per (c) that is non-halting but in reality it is not. > Ergo, the rule (c) is wrong. > That was an example of an input that H correctly determines does halt. -- Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer