Path: news.eternal-september.org!eternal-september.org!feeder3.eternal-september.org!news.quux.org!news.nk.ca!rocksolid2!i2pn2.org!.POSTED!not-for-mail From: joes Newsgroups: comp.theory Subject: Re: Incorrect requirements --- Computing the mapping from the input to HHH(DD) Date: Fri, 9 May 2025 09:48:49 -0000 (UTC) Organization: i2pn2 (i2pn.org) Message-ID: <2b99f70ab35ec939ead52ef88135a2f39e141ad2@i2pn2.org> References: <87msbmeo3b.fsf@nosuchdomain.example.com> <87a57mek8r.fsf@nosuchdomain.example.com> <87seled0zy.fsf@nosuchdomain.example.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Injection-Date: Fri, 9 May 2025 09:48:49 -0000 (UTC) Injection-Info: i2pn2.org; logging-data="3780990"; mail-complaints-to="usenet@i2pn2.org"; posting-account="nS1KMHaUuWOnF/ukOJzx6Ssd8y16q9UPs1GZ+I3D0CM"; User-Agent: Pan/0.145 (Duplicitous mercenary valetism; d7e168a git.gnome.org/pan2) X-Spam-Checker-Version: SpamAssassin 4.0.0 Am Thu, 08 May 2025 22:34:35 -0500 schrieb olcott: > On 5/8/2025 10:14 PM, Mike Terry wrote: >> On 09/05/2025 03:13, olcott wrote: >>> On 5/8/2025 8:30 PM, Keith Thompson wrote: >>>> olcott writes: >>>>> On 5/8/2025 6:49 PM, Keith Thompson wrote: >>>>>> olcott writes: >> His simulation is in fact a single-stepped x86 instruction simulation, >> where the stepping of each x86 instruction is under the HHH's control. >> HHH can continue stepping the simulation until its target returns, in >> which case the situation is logically just like direct call, as you >> have described.  Or HHH could step just 3 x86 instructions (say) and >> then decide to return (aka "abort" its simulation).  Let's call that / >> partial/ simulation in contrast with /full/ simulation which you've >> been supposing. > A full simulation of infinite recursion? > I am only doing one tiny idea at a time here. Yeah, so not a full simulation. >>>> In practice, the program will likely crash due to a stack overflow, >>>> unless the compiler implements tail-call optimization, in which case >>>> the program might just run forever -- which also means the >>>> unnecessary return statement will never be reached. >>> Yes you totally have this correctly. >>> None of the dozens of comp.theory people could ever achieve that level >>> of understanding even after three years. That is why I needed to post >>> on comp.lang.c. >> Everybody on comp.theory understands this much. > No one here ever agreed that when 1 or more instructions of DDD are > correctly simulated by HHH that DDD cannot possibly reach its own > "return" instruction. That's wrong as written. HHH cannot simulate DDD returning in a finite number of instructions, it takes infinitely many. >>>> This conclusion relies on my understanding of what you've said about >>>> your code, which I consider to be unreliable. >> >> Hmm, did PO make it clear that when he says >>    "..DDD correctly simulated by HHH cannot >>     possibly REACH its own "return" instruction." >> he is not talking about whether "DDD halts"?  [I.e. halts when run >> directly from main() outside of a simulator.]  No, what he is talking >> about is whether the /step-by-step partial simuation/ of DDD performed >> by HHH proceeds as far as DDD returning. > > When 1 or more steps of DDD are correctly simulated by HHH the simulated > DDD cannot possibly reach its "return" instruction (final halt state). > No one here has agreed to that. Not in several years of coaxing and > elaboration. It's true for a finite number. Aborting is not correct simulation, even if HHH did return that DDD halts. -- Am Sat, 20 Jul 2024 12:35:31 +0000 schrieb WM in sci.math: It is not guaranteed that n+1 exists for every n.