Re: Why does Olcott care about simulation, anyway?

On 03/06/2024 19:03, olcott wrote:

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.

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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.
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PO does not properly understand this distinction.
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 *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*

I do not ignore the above.  I recently posted an example of it: a simulating HD correctly reporting non-halting after detecting a tight loop in the computation represented by its input.
The problem with the above is with YOU.  (You misinterpret/misapply what Sipser says.)
And of course your entire purpose behind quoting the above is just an appeal to authority.  You know that's a fallacy, because from time to time you accuse others of doing it.

 

>
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.

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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*
 

Well, it kinda DOES.  This is just a blatant appeal to authority on your part, so it can rightly be ignored.  I'll say again - if you have some argument to make, argue it yourself in your own words rather than attempting to shut down discussion through appeal to authority.
[Perhaps Hehner/Stoddart are just idiots who got things wrong, or much more likely you've completely misinterpreted what they're saying, or you've misunderstood the context or whatever and you are the idiot.  The bottom line is THEY ARE NOT HERE ARGUING ANY CASE SO WHAT YOU SAY THEY BELIEVE IS TOTALLY IRRELEVANT.  And there's no need for anyone to get into discussions over whether it is Hehner/Stoddart or yourself who is confused...]
Mike.