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Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail From: olcott <polcott333@gmail.com> Newsgroups: comp.theory Subject: Re: How to write a self-referencial TM? Date: Fri, 16 May 2025 10:47:34 -0500 Organization: A noiseless patient Spider Lines: 103 Message-ID: <1007mmm$3qb7l$20@dont-email.me> References: <1e4f1a15826e67e7faf7a3c2104d09e9dadc6f06.camel@gmail.com> <1002akp$2i4bk$2@dont-email.me> <479eebef3bd93e82c8fe363908b254b11d15a799.camel@gmail.com> <1002jkk$2k00a$3@dont-email.me> <05e306f20fcb7c88c497e353aaecd36b30fc752a.camel@gmail.com> <10053hb$3759k$1@dont-email.me> <879b3c552bad9da9885e41a298b570c92bef1aaf.camel@gmail.com> <1005egk$39app$1@dont-email.me> <fc1c33876fb2863cf4b3976a243042e11b8529cc.camel@gmail.com> <1006qe7$3lja6$1@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Fri, 16 May 2025 17:47:35 +0200 (CEST) Injection-Info: dont-email.me; posting-host="a793c50ac46b1404361ae4f1062ef558"; logging-data="4009205"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+yyCZczhZQ4dZFiIyHwAKg" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:pljr18JcbVmyjgo/h6O6dcgruzA= Content-Language: en-US X-Antivirus: Norton (VPS 250516-4, 5/16/2025), Outbound message In-Reply-To: <1006qe7$3lja6$1@dont-email.me> X-Antivirus-Status: Clean Bytes: 5094 On 5/16/2025 2:45 AM, Mikko wrote: > On 2025-05-15 20:08:54 +0000, wij said: > >> On Thu, 2025-05-15 at 14:15 -0500, olcott wrote: >>> On 5/15/2025 1:49 PM, wij wrote: >>>> On Thu, 2025-05-15 at 17:08 +0100, Mike Terry wrote: >>>>> On 14/05/2025 18:53, wij wrote: >>>>>> On Wed, 2025-05-14 at 12:24 -0500, olcott wrote: >>>>>>> On 5/14/2025 11:43 AM, wij wrote: >>>>>>>> On Wed, 2025-05-14 at 09:51 -0500, olcott wrote: >>>>>>>>> On 5/14/2025 12:13 AM, wij wrote: >>>>>>>>>> Q: Write a turing machine that performs D function (which >>>>>>>>>> calls itself): >>>>>>>>>> >>>>>>>>>> void D() { >>>>>>>>>> D(); >>>>>>>>>> } >>>>>>>>>> >>>>>>>>>> Easy? >>>>>>>>>> >>>>>>>>>> >>>>>>>>> >>>>>>>>> That is not a TM. >>>>>>>> >>>>>>>> It is a C program that exists. Therefore, there must be a >>>>>>>> equivalent TM. >>>>>>>> >>>>>>>>> To make a TM that references itself the closest >>>>>>>>> thing is a UTM that simulates its own TM source-code. >>>>>>>> >>>>>>>> How does a UTM simulate its own TM source-code? >>>>>>>> >>>>>>> >>>>>>> You run a UTM that has its own source-code on its tape. >>>>>> >>>>>> What is exactly the source-code on its tape? >>>>>> >>>>> >>>>> Every UTM has some scheme which can be applied to a (TM & input >>>>> tape) that is to be simulated. >>>>> The >>>>> scheme says how to turn the (TM + input tape) into a string of >>>>> symbols that represent that >>>>> computation. >>>>> >>>>> So to answer your question, the "source-code on its tape" is the >>>>> result of applying the UTM's >>>>> particular scheme to the combination (UTM, input tape) that is to >>>>> be simulated. >>>>> >>>>> If you're looking for the exact string symbols, obviously you would >>>>> need to specify the exact >>>>> UTM >>>>> being used, because every UTM will have a different answer to your >>>>> question. >>>>> >>>>> >>>>> Mike. >>>> >>>> People used to say UTM can simulate all TM. I was questing such a UTM. >>>> Because you said "Every UTM ...", so what is the source of such UTM? >>>> >>>> >>> >>> The TM description language is more accurately >>> referred to as the TM specification language. >>> >>> A UTM is a hypothetical thing that is specified >>> to have some source source-code that it operates >>> on yet none of the details of this are ever >>> fully elaborated. >>> >>> That is why I needed to use the x86 language >>> as a fully specified proxy. With my x86utm >>> operating system we make a 100% concrete >>> simulating termination analyzer such that >>> zero of the details are "abstracted away". >>> >>> It is the details that have been "abstracted away" >>> by the abstractions that cause the conventional >>> halting problem proofs to be insufficiently >>> understood. >> >> Unfortunely, refuting HP suggests halting decider is a real thing. >> Proving by "abstracted away" the real part? > > In which way can a proof that a halting decider does not exist > suggest that a halting decider is a real thing? > > The concept of halting decider is a real concept in the same sense > as Arsitotle's concept of unicorn is a real concept but does that > mean that a unicorn and a halting decider are real things? > I have only refuted the standard proof. A halt decider HHH having a domain of DD and DDD correctly maps its inputs to the actual behavior that they actually specify. -- Copyright 2025 Olcott "Talent hits a target no one else can hit; Genius hits a target no one else can see." Arthur Schopenhauer