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From: Mikko <mikko.levanto@iki.fi>
Newsgroups: comp.theory
Subject: Re: DDD specifies recursive emulation to HHH and halting to HHH1
Date: Mon, 31 Mar 2025 11:47:01 +0300
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On 2025-03-30 20:32:07 +0000, olcott said:

> On 3/30/2025 1:52 PM, Richard Damon wrote:
>> On 3/30/25 2:27 PM, olcott wrote:
>>> On 3/30/2025 3:12 AM, joes wrote:
>>>> Am Sat, 29 Mar 2025 16:46:26 -0500 schrieb olcott:
>>>>> On 3/29/2025 3:14 PM, dbush wrote:
>>>>>> On 3/29/2025 4:01 PM, olcott wrote:
>>>> 
>>>>>>> We can know that when this adapted UTM simulates a finite number of
>>>>>>> steps of its input that this finite number of steps were simulated
>>>>>>> correctly.
>>>>>> And therefore does not do a correct UTM simulation that matches the
>>>>>> behavior of the direct execution as it is incomplete.
>>>>> It is dishonest to expect non-terminating inputs to complete.
>>>> A complete simulation of a nonterminating input doesn't halt.
>>>> 
>>>>>>>> 2) changing the input is not allowed
>>>>>>> The input is unchanged. There never was any indication that the input
>>>>>>> was in any way changed.
>>>>>> False, if the starting function calls UTM and UTM changes, you're
>>>>>> changing the input.
>>>>> When UTM1 is a UTM that has been adapted to only simulate a finite
>>>>> number of steps
>>>> So not an UTM.
>>>> 
>>>>> and input D calls UTM1 then the behavior of D simulated
>>>>> by UTM1 never reaches its final halt state.
>>>>> When D is simulated by ordinary UTM2 that D does not call Then D reaches
>>>>> its final halt state.
>>>> Doesn't matter if it calls it, but if the UTM halts.
>>>> 
>>>>>> Changing the input is not allowed.
>>>>> I never changed the input. D always calls UTM1.
>>>>> thus is the same input to UTM1 as it is to UTM2.
>>>> You changed UTM1, which is part of the input D.
>>>> 
>>> 
>>> UTM1 simulates D that calls UTM1
>>> simulated D NEVER reaches final halt state
>>> 
>>> UTM2 simulates D that calls UTM1
>>> simulated D ALWAYS reaches final halt state
>>> 
>> 
>> Only because UTM1 isn't actually a UTM, but a LIE since it only does a 
>> partial simulation, not a complete as REQURIED by the definition of a 
>> UTM.
>> 
> 
> _DDD()
> [00002172] 55         push ebp      ; housekeeping
> [00002173] 8bec       mov  ebp,esp  ; housekeeping
> [00002175] 6872210000 push 00002172 ; push DDD
> [0000217a] e853f4ffff call 000015d2 ; call HHH(DDD)
> [0000217f] 83c404     add  esp,+04
> [00002182] 5d         pop  ebp
> [00002183] c3         ret
> Size in bytes:(0018) [00002183]
> 
> DDD EMULATED BY HHH DOES SPECIFY THAT IT
> CANNOT POSSIBLY REACH ITS OWN FINAL HALT STATE.

No, it does not. HHH misintepretes, contrary to the semantics of x86,
the specification to mean that.

-- 
Mikko