Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: olcott Newsgroups: comp.theory Subject: Re: Every sufficiently competent C programmer knows --- Semantic Property of Finite String Date: Wed, 12 Mar 2025 18:28:20 -0500 Organization: A noiseless patient Spider Lines: 140 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 00:28:21 +0100 (CET) Injection-Info: dont-email.me; posting-host="c857a159987cd29a4265e3ac68f94ca5"; logging-data="3018624"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/JP+OTTAb2RjeD5NVo8nVl" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:gjYgNgNrb2sF0DjNzmBIPRLzenE= X-Antivirus: Norton (VPS 250312-2, 3/12/2025), Outbound message In-Reply-To: X-Antivirus-Status: Clean Content-Language: en-US Bytes: 7466 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. -- Copyright 2025 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer