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Path: ...!weretis.net!feeder9.news.weretis.net!i2pn.org!i2pn2.org!.POSTED!not-for-mail From: Richard Damon <richard@damon-family.org> Newsgroups: comp.theory Subject: Re: DDD correctly simulated by HH cannot possibly halt Date: Tue, 11 Jun 2024 21:46:05 -0400 Organization: i2pn2 (i2pn.org) Message-ID: <v4aukt$3nf9m$4@i2pn2.org> References: <v428vv$2no74$2@dont-email.me> <v43ib7$38hnd$1@dont-email.me> <v44da3$3i5jo$1@dont-email.me> <v46b4u$99o6$1@dont-email.me> <v474uv$ggn5$8@dont-email.me> <v490b8$v2i4$1@dont-email.me> <v4a192$157ic$4@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Wed, 12 Jun 2024 01:46:05 -0000 (UTC) Injection-Info: i2pn2.org; logging-data="3915062"; mail-complaints-to="usenet@i2pn2.org"; posting-account="diqKR1lalukngNWEqoq9/uFtbkm5U+w3w6FQ0yesrXg"; User-Agent: Mozilla Thunderbird In-Reply-To: <v4a192$157ic$4@dont-email.me> Content-Language: en-US X-Spam-Checker-Version: SpamAssassin 4.0.0 Bytes: 5547 Lines: 118 On 6/11/24 1:24 PM, olcott wrote: > On 6/11/2024 3:02 AM, Mikko wrote: >> On 2024-06-10 15:09:19 +0000, olcott said: >> >>> On 6/10/2024 2:48 AM, Mikko wrote: >>>> On 2024-06-09 14:13:23 +0000, olcott said: >>>> >>>>> On 6/9/2024 1:33 AM, Fred. Zwarts wrote: >>>>>> Op 08.jun.2024 om 20:47 schreef olcott: >>>>>>> Before we can get to the behavior of the directly executed >>>>>>> DD(DD) we must first see that the Sipser approved criteria >>>>>>> have been met: >>>>>>> >>>>>>> <MIT Professor Sipser agreed to ONLY these verbatim words >>>>>>> 10/13/2022> >>>>>>> If simulating halt decider H correctly simulates its input D >>>>>>> until H correctly determines that its simulated D would never >>>>>>> stop running unless aborted then >>>>>>> >>>>>>> H can abort its simulation of D and correctly report that D >>>>>>> specifies a non-halting sequence of configurations. >>>>>>> </MIT Professor Sipser agreed to ONLY these verbatim >>>>>>> words10/13/2022> >>>>>>> >>>>>>> On 10/14/2022 7:44 PM, Ben Bacarisse wrote: >>>>>>> > I don't think that is the shell game. PO really /has/ an H >>>>>>> > (it's trivial to do for this one case) that correctly determines >>>>>>> > that P(P) *would* never stop running *unless* aborted. >>>>>>> >>>>>>> Try to show how this DD correctly simulated by any HH ever >>>>>>> stops running without having its simulation aborted by HH. >>>>>> >>>>>> Stopping at your first error. So, we can focus on it. Your are >>>>>> asking a question that contradicts itself. >>>>>> A correct simulation of HH that aborts itself, should simulate up >>>>>> to the point where the simulated HH aborts. That is logically >>>>>> impossible. So, either it is a correct simulation and then we see >>>>>> that the simulated HH aborts and returns, or the simulation is >>>>>> incorrect, because it assumes incorrectly that things that happen >>>>>> (abort) do not happen. >>>>>> A premature conclusion. >>>>>> >>>>>> >>>>> >>>>> I have a clearer explanation now that I have gone through >>>>> all of Mikko's posts: (you must know C to understand this) >>>>> >>>>> typedef void (*ptr)(); // pointer to void function >>>>> >>>>> void HHH(ptr P, ptr I) >>>>> { >>>>> P(I); >>>>> return; >>>>> } >>>>> >>>>> void DDD(int (*x)()) >>>>> { >>>>> HHH(x, x); >>>>> return; >>>>> } >>>>> >>>>> int main() >>>>> { >>>>> HHH(DDD,DDD); >>>>> } >>>>> >>>>> In the above Neither DDD nor HHH ever reach their own return >>>>> statement thus never halt. >>>>> >>>>> When HHH is a simulating halt decider then HHH sees that >>>> >>>> As the code above shows, HHH is not a simulating halt decider: >>>> (a) HHH does not simulate, (b) HHH does not decide. >>>> Consequently, you are talking about nothing. >>>> >>> >>> Yes that is correct. I begin with ordinary infinite recursion. >>> If my reviewer does not understand that then they lack sufficient >>> technical competence to review my work. >>> >>> After they first understand infinite recursion then I show how >>> infinite recursion is isomorphic to nested simulation. >> >> To proove an isomorphism required much more effort that proving merely >> what you need to prove. It is easier to prove a claim about recursive >> calls and then transform that proof to a proof about nested simulation. >> Other aspects of an isomorphism are not relevant so hardly worth of a >> proof. >> > > void DDD(int (*x)()) > { > HH(x, x); > } > > _DDD() > [00001de2] 55 push ebp > [00001de3] 8bec mov ebp,esp > [00001de5] 8b4508 mov eax,[ebp+08] > [00001de8] 50 push eax ; push DDD > [00001de9] 8b4d08 mov ecx,[ebp+08] > [00001dec] 51 push ecx ; push DDD > [00001ded] e890f5ffff call 00001382 ; call HH > [00001df2] 83c408 add esp,+08 > [00001df5] 5d pop ebp > [00001df6] c3 ret > Size in bytes:(0021) [00001df6] > > DDD correctly simulated by HH cannot possibly reach its own > simulated "ret" instruction at [00001df6] and terminate normally > and no one can possibly show the detailed steps of how it could. > And the question still is why should we care. Partial simulations do not, by themselves, prove non-halting behavior. So, you are just diverting yourself from the task you claim to be working on.