Re: Why does Olcott care about simulation, anyway?

On 6/3/2024 12:36 PM, Mike Terry wrote:

On 03/06/2024 08:58, Fred. Zwarts wrote:

Op 03.jun.2024 om 02:16 schreef immibis:

The halting problem says you can't find a Turing machine that tells whether executing each other Turing machine will halt. Simulation has nothing to do with the question.

>
Maybe because by using simulation he can shift the attention from the pathological part of the Linz proof, to another halting problem, namely that a simulating decider does not halt because it causes infinite recursion.

 PO's simulating decider does not cause infinite recursion.  That only occurs in the case where the decider performs a FULL simulation of its input, whereas typically for PO his H/HH/... perform PARTIAL simulations, where the decider monitors what is being simulated and breaks off the simulation when a particular condition is observed.
 

Thanks for affirming that. You are my most technically
competent and honest reviewer.

So yes, there is recursive simulation, but not /infinite/ recursion since at each level of simulation the simulator is free to just stop simulating at any time.  In practice this means that the outer simulator H will be the one to break out, since it will always be ahead of all the inner simulations of H in how far it has progressed.  This situation is in contrast with direct call recursion, where the outer caller has no control to break the recursion - it only regains control once the inner calls have all returned.
 PO does not properly understand this distinction.
 

*You can keep ignoring this that does not make it go away*
On 10/13/2022 11:29:23 AM
MIT Professor Michael Sipser agreed this verbatim paragraph is correct
(He has neither reviewed nor agreed to anything else in this paper)
<Professor Sipser agreed>
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.
</Professor Sipser agreed>
*You can ignore the above forever, that does not make it away*

>
His own claim that D does not reach the pathological part (after line 03), displays already that the simulation is unable to process the pathological part. But the simulation introduces a new halting problem (recursive simulation), which he thinks is an answer for the original halting problem.

 You're using PO's phrase "pathological" but that is a bad (misleading) term because it suggests there is something WRONG/BAD (aka sick?) in the situation.  E.g. H processing input which is a description of its own source code.  There is nothing whatsoever wrong with that - it's just that PO gets confused by it and so argues to ban it.  Perhaps there  is an alternative term that doesn't have the deliberate connotation of "sickness".
 Mike.
 

*Two PhD computer science professors disagree*
E C R Hehner. *Problems with the Halting Problem*, COMPUTING2011 Symposium on 75 years of Turing Machine and Lambda-Calculus, Karlsruhe Germany, invited, 2011 October 20-21; Advances in Computer Science and Engineering v.10 n.1 p.31-60, 2013
https://www.cs.toronto.edu/~hehner/PHP.pdf
E C R Hehner. *Objective and Subjective Specifications*
WST Workshop on Termination, Oxford.  2018 July 18.
See https://www.cs.toronto.edu/~hehner/OSS.pdf
Bill Stoddart. *The Halting Paradox*
20 December 2017
https://arxiv.org/abs/1906.05340
arXiv:1906.05340 [cs.LO]
*You can ignore the above forever, that does not make it away*
--
Copyright 2024 Olcott "Talent hits a target no one else can hit; Genius
hits a target no one else can see." Arthur Schopenhauer