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Groups > comp.theory > #35706

Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard)

Newsgroups comp.theory
Date 2021-07-04 13:30 -0700
References (11 earlier) <sbrlnm$8ae$1@dont-email.me> <sI-dnV3pkoUWX3z9nZ2dnUU7-bHNnZ2d@giganews.com> <793c3404-e817-4375-94c9-c6e8917e4764n@googlegroups.com> <sbt0h3$ci3$1@dont-email.me> <8q-dncvsqrvtiH_9nZ2dnUU7-VvNnZ2d@giganews.com>
Message-ID <fcaee86b-a8a1-4cc6-b0ee-8b5cd09d00aen@googlegroups.com> (permalink)
Subject Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard)
From Malcolm McLean <malcolm.arthur.mclean@gmail.com>

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On Sunday, 4 July 2021 at 21:09:27 UTC+1, olcott wrote:
> On 7/4/2021 2:00 PM, André G. Isaak wrote: 
> > On 2021-07-04 12:24, Malcolm McLean wrote: 
> > 
> >> The execution trace showed two calls to the "halts" subroutine. 
> >> However it was stated that "halts" is a simulating decider. Therefore we 
> >> have one call to halts. It then emulates another call to halts. But the 
> >> second call to "halts" shouldn't appear on the execution trace. It's 
> >> emulated. 
> >> 
> >> So exactly what the decider is doing remains a bit opaque. 
> > 
> > I've tried to get Olcott to clarify exactly what he means by 
> > 'emulate'/'simulate' but to no avail. I'm fairly sure he doesn't mean 
> > what the rest of the world means, but I still am unclear about what he 
> > actually means. 
> > 
> > André 
> >
> Sure everyone knows that an x86 emulator can be anything from a vanilla 
> milkshake machine to a dump truck. What I mean by x86 emulator is 
> software that executes x86 machine language as if this software virtual 
> machine was an actual x86 processor.
> 
What I understand by an emulator is something which spins up a virtual
enviornment - a struct containing registers, an area of memory, and
maybe other bits and bats. Then the core of the program is a switch on the
opcode pointed to by the instruction pointer. It then manipulates the
virtual environment in the same way as a real machine.

So if we see "call 0x12345678" we don't make a jump to address 12345678.
Instead we go to the switch case that handles "call". This will push the
virtual instruction pointer on to a stack, and set it to "12345678". Then on
the next pass the virtual instruction pointer is "12345678" and we load the
instruction at that address and switch on the opcode.

So the emulator doesn't actually make a subroutine call. Of course you can
create emulations of emulations using this system, to any depth you like
until you run out of emeory. But the emulator is simply going round in an
instruction fetch / decode / execute loop.

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Thread

Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 10:19 -0500
  Re: Could H correctly decide that P never halts? wij <wyniijj@gmail.com> - 2021-07-03 08:25 -0700
    Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 10:32 -0500
      Re: Could H correctly decide that P never halts? Richard Damon <Richard@Damon-Family.org> - 2021-07-03 11:56 -0400
        Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 11:19 -0500
          Re: Could H correctly decide that P never halts? Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-03 18:28 +0200
            Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 11:51 -0500
              Re: Could H correctly decide that P never halts? Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-03 19:18 +0200
                Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 12:19 -0500
                Re: Could H correctly decide that P never halts? Bonita Montero <Bonita.Montero@gmail.com> - 2021-07-03 19:33 +0200
          Re: Could H correctly decide that P never halts? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-03 19:10 +0100
            Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 13:49 -0500
          Re: Could H correctly decide that P never halts? Richard Damon <Richard@Damon-Family.org> - 2021-07-03 14:29 -0400
  Re: Could H correctly decide that P never halts? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-03 17:25 +0100
    Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 11:49 -0500
      Re: Could H correctly decide that P never halts? Richard Damon <Richard@Damon-Family.org> - 2021-07-03 14:17 -0400
        Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ] olcott <NoOne@NoWhere.com> - 2021-07-03 14:08 -0500
          Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ] Richard Damon <Richard@Damon-Family.org> - 2021-07-03 15:43 -0400
            Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-03 15:37 -0500
              Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-03 17:58 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-03 17:20 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-03 18:55 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Mr Flibble <flibble@reddwarf.jmc> - 2021-07-03 23:57 +0100
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-03 18:13 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-03 19:04 -0400
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] olcott <NoOne@NoWhere.com> - 2021-07-03 18:34 -0500
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] Richard Damon <Richard@Damon-Family.org> - 2021-07-03 20:06 -0400
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] olcott <NoOne@NoWhere.com> - 2021-07-03 19:26 -0500
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] Richard Damon <Richard@Damon-Family.org> - 2021-07-03 21:21 -0400
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] olcott <NoOne@NoWhere.com> - 2021-07-03 20:41 -0500
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] Richard Damon <Richard@Damon-Family.org> - 2021-07-03 22:13 -0400
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] olcott <NoOne@NoWhere.com> - 2021-07-03 21:22 -0500
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] Richard Damon <Richard@Damon-Family.org> - 2021-07-03 23:24 -0400
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] olcott <NoOne@NoWhere.com> - 2021-07-03 22:32 -0500
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] Richard Damon <Richard@Damon-Family.org> - 2021-07-04 06:40 -0400
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] olcott <NoOne@NoWhere.com> - 2021-07-04 09:24 -0500
                Re: Could H correctly decide that P never halts? [ prerequisites to understanding me] Richard Damon <Richard@Damon-Family.org> - 2021-07-04 14:50 -0400
              Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) André G. Isaak <agisaak@gm.invalid> - 2021-07-03 19:14 -0600
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-03 20:38 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) André G. Isaak <agisaak@gm.invalid> - 2021-07-03 22:14 -0600
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) André G. Isaak <agisaak@gm.invalid> - 2021-07-03 22:18 -0600
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-03 23:18 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) André G. Isaak <agisaak@gm.invalid> - 2021-07-04 00:50 -0600
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-04 09:15 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) André G. Isaak <agisaak@gm.invalid> - 2021-07-04 10:31 -0600
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-05 08:07 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-07-04 11:24 -0700
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) André G. Isaak <agisaak@gm.invalid> - 2021-07-04 13:00 -0600
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-04 15:09 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-07-04 13:30 -0700
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-05 08:23 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2021-07-05 07:18 -0700
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-05 09:31 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 11:10 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-05 10:18 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 11:29 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 12:53 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-05 12:13 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) André G. Isaak <agisaak@gm.invalid> - 2021-07-04 14:55 -0600
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) "dklei...@gmail.com" <dkleinecke@gmail.com> - 2021-07-04 18:03 -0700
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-04 20:42 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-04 22:31 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 08:05 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-05 08:40 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 12:13 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Jeff Barnett <jbb@notatt.com> - 2021-07-04 23:20 -0600
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2021-07-05 18:49 +0100
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Jeff Barnett <jbb@notatt.com> - 2021-07-05 15:17 -0600
                Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-05 17:38 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-04 23:52 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 10:36 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-05 09:51 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 11:36 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) olcott <NoOne@NoWhere.com> - 2021-07-05 08:18 -0500
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 12:11 -0400
                Re: Could H correctly decide that P never halts? [ Why can H ignore its own behavior? ](my thanks to Richard) Richard Damon <Richard@Damon-Family.org> - 2021-07-04 15:02 -0400
      Re: Could H correctly decide that P never halts? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-03 21:20 +0100
        Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 16:21 -0500
          Re: Could H correctly decide that P never halts? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-04 01:23 +0100
            Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-03 19:30 -0500
              Re: Could H correctly decide that P never halts? [ already agreed ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-04 17:46 +0100
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-04 12:00 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-05 02:04 +0100
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-04 20:57 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-05 03:14 +0100
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-04 21:28 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-04 22:33 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-04 22:09 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 07:33 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-05 08:38 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 10:57 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-05 09:59 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 11:34 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 13:16 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-05 12:48 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 14:36 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 12:18 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-05 23:58 +0100
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-05 19:54 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 21:29 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-06 03:35 +0100
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-05 22:30 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-06 06:47 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] Daniel Pehoushek <pehoushek1@gmail.com> - 2021-07-06 04:15 -0700
                Re: Could H correctly decide that P never halts? [ already agreed ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-06 13:23 +0100
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 07:21 -0400
                Re: Could H correctly decide that P never halts? [ halting criteria ] olcott <NoOne@NoWhere.com> - 2021-07-05 08:26 -0500
                Re: Could H correctly decide that P never halts? [ halting criteria ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 10:50 -0400
                Re: Could H correctly decide that P never halts? [ halting criteria ] olcott <NoOne@NoWhere.com> - 2021-07-05 09:56 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 10:30 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] olcott <NoOne@NoWhere.com> - 2021-07-05 09:33 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] Richard Damon <Richard@Damon-Family.org> - 2021-07-05 11:02 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] (correction) olcott <NoOne@NoWhere.com> - 2021-07-05 09:35 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] (correction) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 12:38 -0400
                Re: Could H correctly decide that P never halts? [ already agreed ] (correction) olcott <NoOne@NoWhere.com> - 2021-07-05 12:10 -0500
                Re: Could H correctly decide that P never halts? [ already agreed ] (correction) Richard Damon <Richard@Damon-Family.org> - 2021-07-05 13:43 -0400
                Re: Could H correctly decide that P never halts? [ Richard's excellent summation ] olcott <NoOne@NoWhere.com> - 2021-07-05 19:12 -0500
  Re: Could H correctly decide that P never halts? Siri Cruise <chine.bleu@yahoo.com> - 2021-07-03 11:01 -0700
    Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 13:15 -0500
      Re: Could H correctly decide that P never halts? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-03 21:09 +0100
        Re: Could H correctly decide that P never halts? [ incorrect question ] olcott <NoOne@NoWhere.com> - 2021-07-03 16:06 -0500
          Re: Could H correctly decide that P never halts? [ incorrect question ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-04 01:44 +0100
            Re: Could H correctly decide that P never halts? [ incorrect question ] olcott <NoOne@NoWhere.com> - 2021-07-03 19:59 -0500
              Re: Could H correctly decide that P never halts? [ incorrect question ] Mr Flibble <flibble@reddwarf.jmc> - 2021-07-04 02:34 +0100
                Re: Could H correctly decide that P never halts? [ incorrect question ] olcott <NoOne@NoWhere.com> - 2021-07-03 20:46 -0500
              Re: Could H correctly decide that P never halts? [ incorrect question ] Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-04 17:45 +0100
    Re: Could H correctly decide that P never halts? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-03 19:15 +0100
      Re: Could H correctly decide that P never halts? olcott <NoOne@NoWhere.com> - 2021-07-03 13:58 -0500
    Re: Could H correctly decide that P never halts? Siri Cruise <chine.bleu@yahoo.com> - 2021-07-03 22:37 -0700
      Re: Could H correctly decide that P never halts? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-07-04 14:14 +0100

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