int Simulate(u32 P, u32 I)
{ ((void(*)(u32))P)(I);
return 1;
}

// Simplified Linz Ĥ (Linz:1990:319)
void H_Hat(u32 P)
{ // Linz H as a simulating partial halt decider
u32 Input_Halts = H(P, P);
if (Input_Halts)
HERE: goto HERE;
}

void H_Hat2(u32 P)
{ u32 Input_Halts = Simulate(P, P);
if (Input_Halts)
HERE: goto HERE;
}

int main()
{ H_Hat2((u32)H_Hat2);
H_Hat((u32)H_Hat);
}

Anyone that knows C programming very well will know that line 1 of main
won't halt and 2 of main will only halt if simulating partial halt
decider H stops simulating H_Hat(). A simulating halt decider that never
stops simulating its input is simply a simulator on this input.

When we know that the UTM simulation of TM Description P on input I
would never halt we know that the execution of TM P(I) would never halt.

On this basis we know that any computation that must have its simulation
aborted to prevent its otherwise infinite execution is correctly
rejected as non-halting.

Linz, Peter 1990. An Introduction to Formal Languages and Automata.
Lexington/Toronto: D. C. Heath and Company.

Halting problem undecidability and infinitely nested simulation
https://www.researchgate.net/publication/351947980_Halting_problem_undecidability_and_infinitely_nested_simulation

--
Copyright 2021 Pete Olcott "Great spirits have always encountered
violent opposition from mediocre minds." Einstein