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Re: How is H(P,P)==0 correct even though P(P) stops running?

From André G. Isaak <agisaak@gm.invalid>
Newsgroups comp.theory
Subject Re: How is H(P,P)==0 correct even though P(P) stops running?
Date 2021-07-22 17:08 -0600
Organization Christians and Atheists United Against Creeping Agnosticism
Message-ID <sdctpp$cjt$1@dont-email.me> (permalink)
References <prednSOZ5uphDmT9nZ2dnUU7-bvNnZ2d@giganews.com> <sdcfsf$3bh$1@dont-email.me> <uridnU-UGa5Uc2T9nZ2dnUU7-XXNnZ2d@giganews.com>

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On 2021-07-22 16:18, olcott wrote:
> On 7/22/2021 2:11 PM, André G. Isaak wrote:
>> On 2021-07-22 09:51, olcott wrote:
>>> How is H(P,P)==0 correct even though P(P) stops running?
>>>
>>> (a) The reason that P of int main(){ P(P); } it is construed as 
>>> halting is that it reaches its final state.
>>>
>>> (b) The reason that it reaches its final state is that H(P,P) returns 
>>> zero.
>>>
>>> (c) The reason that H(P,P) returns zero is that the correct pure 
>>> simulation of its input can't possibly reach its final state.
>>>
>>> (d) When the pure simulation of an input can't possibly ever reach 
>>> its final state then this input never halts.
>>
>> A 'pure simulation' of its inputs is NOT what you describe below. A 
>> pure simulation of P(P) behaves *identically* to P(P). They both halt 
>> (see below for explanation).
>>
> 
> *Pathological Input* to a halt decider is defined as any input that was 
> defined to do the opposite of whatever its corresponding halt decider 
> decides.

There's nothing "pathological" about the transformation which derives 
H_Hat from H. And you cannot formally define something in terms of the 
"intent" of the designer. That simply isn't present in a Turing Machine. 
H_Hat is simply an algorithm that does what it does.

>     Now we construct a new Turing machine D with H as a subroutine.
>     This new TM calls H to determine what M does when the input to
>     M is its own description ⟨M⟩. Once D has determined this information,
>     it does the opposite.  (Sipser:1997:165)
> 
> This question can only be correctly answered after the pathology has 
> been removed. When a halt decider only acts as a pure simulator of its 
> input until after its halt status decision is made there is no feedback 
> loop of back channel communication between the halt decider and its 
> input that can prevent a correct halt status decision.
> 
> It can be seen that while H(P,P) acts as a pure x86 emulator of its 
> input that its input cannot possibly reach its final state.

You need to stop conflating the Halt decider H with the *copy* of H 
inside of P. They are not the same thing.

You really don't seem to grasp how P is supposed to be derived.

We start by making a *copy* of all of the state transitions of H. We 
then prepend a number of transitions to the beginning of this which 
duplicates the input string. Finally, we remove one of the final states 
of the original H (meaning it is no longer H) and replace that with two 
states which loop indefinitely.

What we now have is a *single* TM P which exists *entirely independent* 
of H and which performs a computation entirely distinct from H. It 
doesn't 'call' H since that is not possible for Turing machines. It 
would really be best to not even talk about the 'embedded H' since this 
isn't really a halt decider anymore; it's just one portion of the state 
transitions of P. Moreover, P(P) must be able to run on a system in 
which H is entirely absent (or at least a C 'implementation' of it must 
-- there is no 'system' where TMs are concerned). There can be no 
dependency between H and P since they are *separate* TMs.

Any discussion about the halt decider should be referring *only* to H 
and not to *anything* that goes on inside the simulation of its input P 
since that is not a halt decider at all. it is part of the input 
computation, and P does not purport to answer questions about halting. 
It does not purport to answer any question at all.

>>> ∴ The only reason that P of int main(){ P(P); } halts is because 
>>> H(P,P) correctly decided that its input never halts.
>>
>> When run independently H(P,P) isn't even being computed. If you are 
>> referring to the *internal* copy of H contained in P, then that 
>> *incorrectly* decided that its input never halts.
>>
> 
> You keep ignoring the key fact that unless some H aborts some P int 
> main() { P(P); } never halts. This proves that when H[0] aborts the 
> simulation of P[1] that it was necessarily correct to the same degree 
> that we know that 2 == 2 is correct.

But there really only is one H when you run H(P, P). Everything else is 
part of the input P. And H does *not* need to abort P(P), because P(P) 
*as you have already admitted* does reach a final state.

André

-- 
To email remove 'invalid' & replace 'gm' with well known Google mail 
service.

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Thread

How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-22 10:51 -0500
  Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-22 11:15 -0500
    Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-22 10:38 -0700
  Re: How is H(P,P)==0 correct even though P(P) stops running? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-07-22 10:34 -0700
    Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-22 13:16 -0500
      Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-22 11:39 -0700
    Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-24 00:11 -0500
      Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 23:14 -0700
  Re: How is H(P,P)==0 correct even though P(P) stops running? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-22 19:30 +0100
    Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-22 14:17 -0500
      Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-22 12:42 -0700
      Re: How is H(P,P)==0 correct even though P(P) stops running? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-23 00:04 +0100
        Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-22 18:25 -0500
          Re: How is H(P,P)==0 correct even though P(P) stops running? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-23 00:48 +0100
            Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 08:53 -0500
              Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 08:50 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 11:00 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 09:31 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 12:13 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 11:31 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 13:42 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 11:56 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 14:07 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 12:23 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 15:38 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 13:53 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 15:56 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 14:25 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? André G. Isaak <agisaak@gm.invalid> - 2021-07-23 17:49 -0600
                Re: How is H(P,P)==0 correct even though P(P) stops running? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-07-24 03:56 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? Andy Walker <anw@cuboid.co.uk> - 2021-07-24 12:40 +0100
                Re: How is H(P,P)==0 correct even though P(P) stops running? Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-07-24 04:52 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-24 08:55 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Andy Walker <anw@cuboid.co.uk> - 2021-07-24 16:44 +0100
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-24 10:54 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-24 09:08 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-24 08:50 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-24 09:16 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? André G. Isaak <agisaak@gm.invalid> - 2021-07-24 10:31 -0600
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ pure simulator ] olcott <NoOne@NoWhere.com> - 2021-07-24 09:34 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ pure simulator ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 09:25 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? André G. Isaak <agisaak@gm.invalid> - 2021-07-23 17:42 -0600
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 19:26 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? André G. Isaak <agisaak@gm.invalid> - 2021-07-23 19:02 -0600
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 20:32 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 18:42 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 20:50 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 19:28 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 23:38 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 23:17 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar? ] olcott <NoOne@NoWhere.com> - 2021-07-24 09:05 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar? ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 09:31 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] olcott <NoOne@NoWhere.com> - 2021-07-24 12:23 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 11:34 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] olcott <NoOne@NoWhere.com> - 2021-07-24 13:42 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] André G. Isaak <agisaak@gm.invalid> - 2021-07-24 13:07 -0600
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] olcott <NoOne@NoWhere.com> - 2021-07-24 14:22 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 12:38 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] olcott <NoOne@NoWhere.com> - 2021-07-24 15:01 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 13:14 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-25 04:07 +0100
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2021-07-25 21:02 +0100
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-25 21:33 +0100
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ Internals of H ] olcott <NoOne@NoWhere.com> - 2021-07-26 10:08 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 12:21 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] olcott <NoOne@NoWhere.com> - 2021-07-24 14:24 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 12:44 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] olcott <NoOne@NoWhere.com> - 2021-07-24 15:03 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 13:19 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] André G. Isaak <agisaak@gm.invalid> - 2021-07-24 16:10 -0600
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] olcott <NoOne@NoWhere.com> - 2021-07-24 17:31 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [ liar ??? ] André G. Isaak <agisaak@gm.invalid> - 2021-07-24 16:46 -0600
                Re: How is H(P,P)==0 correct even though P(P) stops running? André G. Isaak <agisaak@gm.invalid> - 2021-07-23 19:44 -0600
                Re: How is H(P,P)==0 correct even though P(P) stops running? [focused until mutual agreement ] olcott <NoOne@NoWhere.com> - 2021-07-24 09:23 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [focused until mutual agreement ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 09:33 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? [focused until mutual agreement ] olcott <NoOne@NoWhere.com> - 2021-07-24 12:41 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? [focused until mutual agreement ] Richard Damon <Richard@Damon-Family.org> - 2021-07-24 11:39 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 18:00 -0700
              Re: How is H(P,P)==0 correct even though P(P) stops running? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-23 22:12 +0100
                Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 16:49 -0500
                Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 15:26 -0700
                Re: How is H(P,P)==0 correct even though P(P) stops running? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-25 04:07 +0100
  Re: How is H(P,P)==0 correct even though P(P) stops running? André G. Isaak <agisaak@gm.invalid> - 2021-07-22 13:11 -0600
    Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-22 17:18 -0500
      Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-22 15:46 -0700
      Re: How is H(P,P)==0 correct even though P(P) stops running? André G. Isaak <agisaak@gm.invalid> - 2021-07-22 17:08 -0600
        Re: How is H(P,P)==0 correct even though P(P) stops running? olcott <NoOne@NoWhere.com> - 2021-07-23 09:35 -0500
          Re: How is H(P,P)==0 correct even though P(P) stops running? Richard Damon <Richard@Damon-Family.org> - 2021-07-23 09:48 -0700

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