Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: dbush Newsgroups: comp.theory Subject: Re: Every sufficiently competent C programmer knows --- Semantic Property of Finite String Date: Wed, 12 Mar 2025 19:34:35 -0400 Organization: A noiseless patient Spider Lines: 144 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Thu, 13 Mar 2025 00:34:35 +0100 (CET) Injection-Info: dont-email.me; posting-host="bfda177ea2e5d824256b51a2c43e6950"; logging-data="2957945"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/+ncKM+gNecfa2lZoNu35/" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:mGQaW+ElwUWnrpUWESZo7WenHzk= In-Reply-To: Content-Language: en-US Bytes: 7626 On 3/12/2025 7:28 PM, olcott wrote: > On 3/12/2025 5:36 PM, dbush wrote: >> On 3/12/2025 6:31 PM, olcott wrote: >>> On 3/12/2025 5:03 PM, dbush wrote: >>>> On 3/12/2025 5:38 PM, olcott wrote: >>>>> On 3/12/2025 3:53 PM, dbush wrote: >>>>>> On 3/12/2025 4:29 PM, olcott wrote: >>>>>>> On 3/12/2025 2:16 PM, dbush wrote: >>>>>>>> On 3/11/2025 10:46 PM, olcott wrote: >>>>>>>>> On 3/11/2025 9:41 PM, dbush wrote: >>>>>>>>>> On 3/11/2025 10:39 PM, olcott wrote: >>>>>>>>>>> On 3/11/2025 9:37 PM, dbush wrote: >>>>>>>>>>>> On 3/11/2025 10:36 PM, olcott wrote: >>>>>>>>>>>>> On 3/11/2025 9:32 PM, dbush wrote: >>>>>>>>>>>>>> On 3/11/2025 10:31 PM, olcott wrote: >>>>>>>>>>>>>>> On 3/11/2025 9:18 PM, dbush wrote: >>>>>>>>>>>>>>>> On 3/11/2025 10:06 PM, olcott wrote: >>>>>>>>>>>>>>>>> On 3/11/2025 9:02 PM, dbush wrote: >>>>>>>>>>>>>>>>>> On 3/11/2025 9:41 PM, Richard Heathfield wrote: >>>>>>>>>>>>>>>>>>> On 12/03/2025 01:22, olcott wrote: >>>>>>>>>>>>>>>>>>>> DDD correctly simulated by HHH never reaches its >>>>>>>>>>>>>>>>>>>> own "return" instruction and terminates normally >>>>>>>>>>>>>>>>>>>> in any finite or infinite number of correctly >>>>>>>>>>>>>>>>>>>> simulated steps. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> If it correctly simulates infinitely many steps, it >>>>>>>>>>>>>>>>>>> doesn't terminate. Look up "infinite". >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>> But your task is to decide for /any/ program, not >>>>>>>>>>>>>>>>>>> just DDD. That, as you are so fond of saying, is >>>>>>>>>>>>>>>>>>> 'stipulated', and you can't get out of it. The whole >>>>>>>>>>>>>>>>>>> point of the Entscheidungsproblem is its >>>>>>>>>>>>>>>>>>> universality. Ignore that, and you have nothing. >>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>> Given that his code has HHH(DD) returning 0, >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> THESE ARE THE WORDS ANYONE THAT DODGES THESE >>>>>>>>>>>>>>>>> WORDS WILL BE TAKEN FOR A LIAR >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> void DDD() >>>>>>>>>>>>>>>>> { >>>>>>>>>>>>>>>>>    HHH(DDD); >>>>>>>>>>>>>>>>>    return; >>>>>>>>>>>>>>>>> } >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>> DDD correctly simulated by HHH never reaches its >>>>>>>>>>>>>>>>> own "return" instruction and terminates normally >>>>>>>>>>>>>>>>> in any finite or infinite number of correctly >>>>>>>>>>>>>>>>> simulated steps. >>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>> Changing the input is not allowed. >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> *You are simply lying that any input was ever changed* >>>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>>>>>> You did precisely that when you hypothesize different code >>>>>>>>>>>>>> for HHH. >>>>>>>>>>>>>> >>>>>>>>>>>>>> Changing the input is not allowed. >>>>>>>>>>>>> >>>>>>>>>>>>> *THIS IS WHAT MY ORIGINAL WORDS MEANT* >>>>>>>>>>>>> HHH is the infinite set of every possible C function >>>>>>>>>>>>> that correctly emulates N steps of its input where >>>>>>>>>>>>> N any finite positive integer. >>>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> In other words, you're changing the input. >>>>>>>>>>>> >>>>>>>>>>>> Changing the input is not allowed. >>>>>>>>>>> >>>>>>>>>>> It is an infinite set of HHH/DDD pairs having the >>>>>>>>>>> property that DDD[0] ... DDD[N] never halts. >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> In other words, you're not answering the question that a >>>>>>>>>> solution to the halting problem is required to answer: >>>>>>>>>> >>>>>>>>>> (,Y) maps to 1 if and only if X(Y) halts when executed >>>>>>>>>> directly >>>>>>>>>> (,Y) maps to 0 if and only if X(Y) does not halt when >>>>>>>>>> executed directly >>>>>>>>>> >>>>>>>>> >>>>>>>>> Yes I am yet you refuse to pay anywhere near close >>>>>>>>> enough attention to see how I already fully addressed this. >>>>>>>>> If you pay 100% perfect attention you might get it. >>>>>>>>> >>>>>>>> >>>>>>>> False.  (,null) maps to 1 as per the above requirements, >>>>>>>> but your HHH maps (,null) to 0, therefore it fails to meet >>>>>>>> the requirements. >>>>>>> >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> So no response?  I'll take it that you agree with the above. >>>>> >>>>> Making sure to always give credit where credit is due this >>>>> point in our conversation is the point where I first translated >>>>> my perspective into the semantic property of a finite string. >>>>> >>>>> A decider is required to report on a semantic (or syntactic) >>>>> property of its input finite string (even if Rice incorrectly >>>>> says this is impossible in this case) and not allowed to report >>>>> on any damn thing else. >>>>> >>>>> The fact that DDD calls HHH(DDD) in recursive emulation >>>>> an aspect of the semantics of the input finite string >>>>> that cannot be correctly ignored. >>>>> >>>>> >>>> >>>> Remember the stipulative definition of a solution to the halting >>>> problem: >>>> >>>> >>> >>> Is to map the input finite string to the semantic property >>> of this finite string. Any other mapping contradicts the >>> definition of a decider. >> >> And that property is as follows: >> >> (,Y) maps to 1 if and only if X(Y) halts when executed directly >> (,Y) maps to 0 if and only if X(Y) does not halt when executed >> directly >> >> I should also point out that I never mentioned anything about a >> "decider", simply "a solution to the halting problem".  Neither did Linz. >> > > > Sure everyone knows that a halt decider is not kind of decider at all. > > > So no answer. Then you accept that HHH(DDD)==0 is wrong because it isn't performing the above mapping required to be a solution to the halting problem.