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: Halting Problem: What Constitutes Pathological Input Date: Wed, 7 May 2025 10:40:42 -0500 Organization: A noiseless patient Spider Lines: 71 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 07 May 2025 17:40:43 +0200 (CEST) Injection-Info: dont-email.me; posting-host="ee5137430f56269cd3e6381ddf24cf46"; logging-data="1147811"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18x8Du4QcW7WfJZZdcCDIrX" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:WZH5YEmCBgLfRK8A1yRRDrvQm7o= In-Reply-To: Content-Language: en-US X-Antivirus-Status: Clean X-Antivirus: Norton (VPS 250507-2, 5/7/2025), Outbound message Bytes: 4171 On 5/7/2025 3:57 AM, Mikko wrote: > On 2025-05-06 15:36:00 +0000, olcott said: > >> On 5/6/2025 4:47 AM, Mikko wrote: >>> On 2025-05-05 19:54:55 +0000, olcott said: >>> >>>> On 5/5/2025 2:49 PM, dbush wrote: >>>>> On 5/5/2025 3:38 PM, olcott wrote: >>>>>> On 5/5/2025 2:23 PM, Richard Heathfield wrote: >>>>>>> On 05/05/2025 20:20, olcott wrote: >>>>>>>> Is "halts" the correct answer for H to return?  NO >>>>>>>> Is "does not halt" the correct answer for H to return?  NO >>>>>>>> Both Boolean return values are the wrong answer >>>>>>> >>>>>>> Or to put it another way, the answer is undecidable, QED. >>>>>>> >>>>>>> See? You got there in the end. >>>>>>> >>>>>> >>>>>> Is this sentence true or false: "What time is it?" >>>>>> is also "undecidable" because it is not a proposition >>>>>> having a truth value. >>>>>> >>>>>> Is this sentence true or false: "This sentence is untrue." >>>>>> is also "undecidable" because it is not a semantically sound >>>>>> proposition having a truth value. >>>>>> >>>>>> Can Carol correctly answer “no” to this (yes/no) question? >>>>>> >>>>>> Both Yes and No are the wrong answer proving that >>>>>> the question is incorrect when the context of who >>>>>> is asked is understood to be a linguistically required >>>>>> aspect of the full meaning of the question. >>>>> >>>>> And "does algorthm X with input Y halt when executed directly" has >>>>> a single well defined answer. >>>>> >>>> >>>> That is not even the actual question. >>>> >>>> Does the finite string input DD to HHH specify >>>> a computation that halts? No it does not. >>> >>> That question is a category error. The halting question is not about >>> finite strings but about computations. >> >> HHH must compute the mapping from its finite string >> of x86 code input to the actual behavior that this >> finite string input specifies. > > No, that is not what the halting problem requires. The halting problem > requires that HHH must be given a finite string that tells what HHH > needs to know about DD in order to correctly predict whether DD halts > if it is directly executed. > And for the same reason int sum(int x, int y) { return x + y; } sum(3,2) must report on the sum of 5 + 6 and is not allowed to report on the sum of 3 + 2. This is because Truth is a Democracy and the common misconceptions cast more votes than correct analysis. -- Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer