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On 3/2/2025 2:40 PM, Andy Walker wrote:But YOUR perspective is the incorrect one, as it is againt the definitions.>[the third paragraph]
http://www.cuboid.me.uk/anw/G12FCO/lect18.html
>
[start at the third paragraph], published in 1996, wherein is the proof
that a simulating halt decider can no more exist than any other halt
decider
For these cases, we can turn to our second weapon -- emulation. We want to know whether a program halts, so we try it. If it halts, then we know the answer. If it doesn't halt, then `it must be in a loop', so we monitor its state and `detect the loop'. Sadly, although this is in one sense correct, it is a false dichotomy. At any given moment as the emulation proceeds, we are in one of not two but three states: the program has halted, or it is looping, or it is still running and has not yet entered a loop. It's the third case that kills us -- we just have to keep going, and wait for one of the other two things to happen. The trouble is that it may be that neither of them ever happens -- which is why `it must be in a loop' was in quotes above.
_DD()
[00002133] 55 push ebp ; housekeeping
[00002134] 8bec mov ebp,esp ; housekeeping
[00002136] 51 push ecx ; make space for local
[00002137] 6833210000 push 00002133 ; push DD
[0000213c] e882f4ffff call 000015c3 ; call HHH(DD)
[00002141] 83c404 add esp,+04
[00002144] 8945fc mov [ebp-04],eax
[00002147] 837dfc00 cmp dword [ebp-04],+00
[0000214b] 7402 jz 0000214f
[0000214d] ebfe jmp 0000214d
[0000214f] 8b45fc mov eax,[ebp-04]
[00002152] 8be5 mov esp,ebp
[00002154] 5d pop ebp
[00002155] c3 ret
Size in bytes:(0035) [00002155]
That analysis is derived from an incorrect perspective.
DD emulated by HHH according to the behavior that DD
specifies cannot possibly reach its own "ret" instruction
and terminate normally.
This process computes the mapping from the actual inputAnd the MAPPING is DEFINED to be input -> 1 if UTM(input) halts, and input -> 0 if UTM(input) does not halt.
(not any other damn thing) finite string to the non
terminating behavior that this finite specifies when
it calls its own emulator in recursive emulation.
Another different instance that does not call its ownWhich means you don't understand the fundamental property that all copies of a computation (program + input) do exactly the same thing, as they are not allowed to depend on anything other than there code and the input.
emulator in recursive emulation is not the same damn thing.
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