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Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: "Fred. Zwarts" <F.Zwarts@HetNet.nl> Newsgroups: comp.theory Subject: Re: Turing Machine computable functions apply finite string transformations to inputs VERIFIED FACT Date: Wed, 30 Apr 2025 11:04:11 +0200 Organization: A noiseless patient Spider Lines: 82 Message-ID: <vusp2b$3sjnn$1@dont-email.me> References: <vu6lnf$39fls$2@dont-email.me> <vugvr3$pke9$8@dont-email.me> <4818688e0354f32267e3a5f3c60846ae7956bed2@i2pn2.org> <vuj18i$2lf64$6@dont-email.me> <f0d3f2e87d9a4e0b0f445f60a33d529f41a4fcf7@i2pn2.org> <vuj55m$2lf64$10@dont-email.me> <vuj8h3$2uahf$3@dont-email.me> <vujfuu$35hcg$1@dont-email.me> <65dddfad4c862e6593392eaf27876759b1ed0e69@i2pn2.org> <vujlj0$3a526$1@dont-email.me> <vujln7$32om9$8@dont-email.me> <vujmmm$3a526$2@dont-email.me> <vujmrj$32om9$9@dont-email.me> <vujtcb$3gsgr$1@dont-email.me> <vuju44$3hnda$1@dont-email.me> <vuk47o$3qkbb$1@dont-email.me> <vuk6b6$3l184$1@dont-email.me> <vuls34$1bf1j$4@dont-email.me> <vun87k$2m24h$2@dont-email.me> <vunb06$2fjjl$5@dont-email.me> <vuo57j$3h5l9$2@dont-email.me> <vuoath$3ljma$1@dont-email.me> <vuohgi$3td7u$1@dont-email.me> <vuonh6$2g74$2@dont-email.me> <vupeor$qf60$1@dont-email.me> <vupu0r$18vrc$1@dont-email.me> <vuqj5u$1rljg$1@dont-email.me> <vuqrgb$23cfh$1@dont-email.me> <vuravu$2hkih$2@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Wed, 30 Apr 2025 11:04:12 +0200 (CEST) Injection-Info: dont-email.me; posting-host="8b78eb5fb7d955f8a1d15a6bb24954d6"; logging-data="4083447"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19gdPYMh5KQC4PFsYzXOYmb" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:SumFK77v6jqdsk2pdtHFalpo7co= In-Reply-To: <vuravu$2hkih$2@dont-email.me> Content-Language: nl, en-GB Bytes: 5598 Op 29.apr.2025 om 21:57 schreef olcott: > On 4/29/2025 10:33 AM, Fred. Zwarts wrote: >> Op 29.apr.2025 om 15:11 schreef olcott: >>> On 4/29/2025 2:10 AM, Richard Heathfield wrote: >>>> On 29/04/2025 03:50, olcott wrote: >>>>> On 4/28/2025 3:13 PM, Richard Heathfield wrote: >>>>>> On 28/04/2025 19:30, olcott wrote: >>>>>>> On 4/28/2025 11:38 AM, Richard Heathfield wrote: >>>>>>>> On 28/04/2025 16:01, olcott wrote: >>>>>>>>> On 4/28/2025 2:33 AM, Richard Heathfield wrote: >>>>>>>>>> On 28/04/2025 07:46, Fred. Zwarts wrote: >>>>>>>>>> >>>>>>>>>> <snip> >>>>>>>>>> >>>>>>>>>>> So we agree that no algorithm exists that can determine for >>>>>>>>>>> all possible inputs whether the input specifies a program >>>>>>>>>>> that (according to the semantics of the machine language) >>>>>>>>>>> halts when directly executed. >>>>>>>>>>> Correct? >>>>>>>>>> >>>>>>>>>> Correct. We can, however, construct such an algorithm just as >>>>>>>>>> long as we can ignore any input we don't like the look of. >>>>>>>>>> >>>>>>>>> >>>>>>>>> The behavior of the direct execution of DD cannot be derived >>>>>>>>> by applying the finite string transformation rules specified >>>>>>>>> by the x86 language to the input to HHH(DD). This proves that >>>>>>>>> this is the wrong behavior to measure. >>>>>>>>> >>>>>>>>> It is the behavior THAT IS derived by applying the finite >>>>>>>>> string transformation rules specified by the x86 language >>>>>>>>> to the input to HHH(DD) proves that THE EMULATED DD NEVER HALTS. >>>>>>>> >>>>>>>> The x86 language is neither here nor there. >>>>>>> >>>>>>> Computable functions are the formalized analogue >>>>>>> of the intuitive notion of algorithms, in the sense >>>>>>> that a function is computable if there exists an >>>>>>> algorithm that can do the job of the function, i.e. >>>>>>> *given an input of the function domain it* >>>>>>> *can return the corresponding output* >>>>>>> https://en.wikipedia.org/wiki/Computable_function >>>>>>> >>>>>>> *Outputs must correspond to inputs* >>>>>>> >>>>>>> *This stipulates how outputs must be derived* >>>>>>> Every Turing Machine computable function is >>>>>>> only allowed to derive outputs by applying >>>>>>> finite string transformation rules to its inputs. >>>>>> >>>>>> In your reply to my article, you forgot to address what I actually >>>>>> wrote. I'm not sure you understand what 'reply' means. >>>>>> >>>>>> Still, I'm prepared to give you another crack at it. Here's what I >>>>>> wrote before: >>>>>> >>>>>> What matters is whether a TM can be constructed that can accept an >>>>>> arbitrary TM tape P and an arbitrary input tape D and correctly >>>>>> calculate whether, given D as input, P would halt. Turing proved >>>>>> that such a TM cannot be constructed. >>>>>> >>>>>> This is what we call the Halting Problem. >>>>>> >>>>> >>>>> Yet it is H(P,D) and NOT P(D) that must be measured. >>>> >>>> Nothing /has/ to be measured. P's behaviour (halts, doesn't halt) >>>> when given D as input must be /established/. >>> >>> No H can possibly see the behavior of P(D) >>> when-so-ever D has defined a pathological >>> relationship with H this >> >> makes it impossible for H to see the behaviour of P(D). >> The behaviour of P(D) does not change, but H does not see it. > > H MUST REPORT ON THE BEHAVIOR THAT IT DOES SEE > That is your error. H must report on the behaviour specified in the input. Bugs in H do not change the behaviour specified in the input. H just fails to see it.