Path: ...!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: olcott Newsgroups: comp.theory Subject: Re: Simulating termination analyzers by dummies --- What does halting mean? Date: Thu, 20 Jun 2024 00:40:28 -0500 Organization: A noiseless patient Spider Lines: 55 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Thu, 20 Jun 2024 07:40:29 +0200 (CEST) Injection-Info: dont-email.me; posting-host="f3edc3033c9d2f90d2fdc1ea5e7f24e7"; logging-data="2572133"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/KiLsE55JXffMQLV2yxKfW" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:3Qh6Z8pJ0kRFohq8UkeZJA8m6GU= Content-Language: en-US In-Reply-To: Bytes: 3841 On 6/20/2024 12:29 AM, Mikko wrote: > On 2024-06-19 14:05:29 +0000, olcott said: > >> On 6/19/2024 4:29 AM, Alan Mackenzie wrote: >>> olcott wrote: >>>> On 6/18/2024 4:36 PM, Alan Mackenzie wrote: >>>>> [ Followup-To: set ] >>> >>>>> In comp.theory olcott wrote: >>>>>> On 6/18/2024 12:57 PM, joes wrote: >>>>>>> Am Tue, 18 Jun 2024 12:25:44 -0500 schrieb olcott: >>>>>>>> On 6/18/2024 12:06 PM, joes wrote: >>>>>>>> void DDD() >>>>>>>> { >>>>>>>> H0(DDD); >>>>>>>> } >>>>>>>> DDD correctly simulated by any H0 cannot possibly halt. >>>>>>>>> DDD halts iff H0 halts. >>> >>>>>>> So H0 returns "doesn't halt" to DDD, which then stops running, >>>>>>> so H0 should have returned "halts". >>> >>>>>> This was three messages ago. >>>>>> I had to make sure that you understood that halting >>>>>> does not mean stopping for any reason and only includes >>>>>> the equivalent of terminating normally. >>> >>>>> No.  You're wrong, here.  A turing machine is either running or it's >>>>> halted.  There's no third alternative.  If your C programs are not >>>>> in one >>>>> of these two states, they're not equivalent to turing machines. >>> >>>> Although I agree with this there seems to be nuances of >>>> disagreement across the experts. >>> >>> I doubt that very much.  The whole point of turing machines is to remove >>> ambiguity and unneeded features from the theory of computation.  A third >>> alternative state is unneeded. >>> >> >> Some people say that a TM can halt in a non-final state. > > People may use different words to express the same facts. What some > people call "halting in a non-final state" is called "rejecting" by > some other people. But the facts are what they are independently of > the words used to express them. > Ambiguity and vagueness make communication less effective. I use C because there are zero gaps in exactly what it means. -- Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer