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computers / / Concise refutation of halting problem proofs V43 [computer scientist]

o Concise refutation of halting problem proofs V43 [computer scientist]olcott

Subject: Concise refutation of halting problem proofs V43 [computer scientist]
From: olcott
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Date: Sat, 1 Jan 2022 21:09 UTC
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Showing how the Linz Ĥ can be correctly decided as non-halting

Revised Linz H halt deciding criteria (My criteria Ben's notation)
H.q0 wM w ⊢* H.qy iff UTM(wM, w) halts
H.q0 wM w ⊢* H.qn iff UTM(wM, w) does not halt

For simplicity we will refer to the copy of Linz H at Ĥ.qx embedded_H.
embedded_H correctly determines that its input ⟨Ĥ⟩ ⟨Ĥ⟩ never halts.

Simplified syntax adapted from bottom of page 319:
Ĥ.q0 ⟨Ĥ⟩ ⊢* Ĥ.qx ⟨Ĥ⟩ ⟨Ĥ⟩ ⊢* Ĥ.qy ∞
Ĥ.q0 ⟨Ĥ⟩ ⊢* Ĥ.qx ⟨Ĥ⟩ ⟨Ĥ⟩ ⊢* Ĥ.qn

If embedded_H would never stop simulating its input ⟨Ĥ⟩ ⟨Ĥ⟩
this input would never reach a final state and stop running.

These steps would keep repeating:
Ĥ copies its input ⟨Ĥ⟩ to ⟨Ĥ⟩ then embedded_H simulates ⟨Ĥ⟩ ⟨Ĥ⟩...

computation that halts
....the Turing machine will halt whenever it enters a final state (Linz:1990:234)

That the pure simulation of an input would never reaches its final state conclusively proves that this input specifies a non-halting computation.

This proves that the input ⟨Ĥ⟩ ⟨Ĥ⟩ to embedded_H maps to Ĥ.qn

Peter Linz HP Proof

Copyright 2021 Pete Olcott

Talent hits a target no one else can hit;
Genius hits a target no one else can see.
Arthur Schopenhauer

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