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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: DD correctly simulated by HH --- never stops running without aborting its simulation
Date: Fri, 7 Jun 2024 09:04:33 +0300
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On 2024-06-06 18:49:32 +0000, Rafael Doofenschmirtz said:

> On 6/06/24 20:35, olcott wrote:
>> <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>
>> 
>> *Try to show how this DD correctly simulated by any HH ever*
>> *stops running without having its simulation aborted by HH*
>> 
>> _DD()
>> [00001e12] 55         push ebp
>> [00001e13] 8bec       mov  ebp,esp
>> [00001e15] 51         push ecx
>> [00001e16] 8b4508     mov  eax,[ebp+08]
>> [00001e19] 50         push eax      ; push DD
>> [00001e1a] 8b4d08     mov  ecx,[ebp+08]
>> [00001e1d] 51         push ecx      ; push DD
>> [00001e1e] e85ff5ffff call 00001382 ; call HH
>> 
> 
> after HH returns 0, the program counter proceeds to address 00001e23, 
> and then, a few instructions later DD also returns

If HH ever returns. The challenge does not specify anything about
HH other than it simulates the same DD. In particular, the last
shown line may cause HH to simulate itself, depending on how HH
interpretes it.

-- 
Mikko