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Groups > comp.theory > #119108
| From | Richard Heathfield <rjh@cpax.org.uk> |
|---|---|
| Newsgroups | comp.theory |
| Subject | Re: How to write a self-referencial TM? |
| Date | 2025-05-14 22:28 +0100 |
| Organization | Fix this later |
| Message-ID | <10031uo$2n1is$1@dont-email.me> (permalink) |
| References | (6 earlier) <8c7a8437e78a5b798cc23d77a8e1b6080e59ab0e.camel@gmail.com> <1002nvo$2k04b$5@dont-email.me> <87plgb9d4i.fsf@nosuchdomain.example.com> <1002tma$2k04c$5@dont-email.me> <87ldqyapfk.fsf@nosuchdomain.example.com> |
On 14/05/2025 21:49, Keith Thompson wrote: > Richard Heathfield <rjh@cpax.org.uk> writes: <snip> >> >> In the Real World, tapes can't be infinite, so an implementor has to >> decide how long 'long enough' is. > > TM's don't necessarily operate in the Real World. Of course. HP is a thought experiment, not an exercise for hardware engineers (or indeed software engineers). I just can't help turning my thoughts in that direction. > >> If the TM's alphabet consisted of 256 discrete symbols (no reason why >> not) a megabyte would give you a disk-based 'tape' a million cells >> long. >> >> Ought to be enough for `take one down and pass it around'. > > Sure. "Infinite tape" might be more precisely expressed as > "sufficient tape". Quite so. > But a TM that advances in one direction along > the tape in a loop will require more than any finite length of tape > if you leave it running long enough, though the amount of tape it > consumes in any finite number of steps is still finite. For that > kind of TM in particular, "infinite tape" is a convenient shorthand. All acknowledged, all agreed. Using a highly questionable collection of approximations about the physical properties of 4mm mylar tape and the number of atoms in the universe, I calculated that by devoting /everything/ to this tape we could make it 5285412262156448202959830866807610993657505285 lightyears long (exACtly, of course). It's still a long way off infinite, but I think it could possibly qualify as 'long enough'. -- Richard Heathfield Email: rjh at cpax dot org dot uk "Usenet is a strange place" - dmr 29 July 1999 Sig line 4 vacant - apply within
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How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-14 13:13 +0800
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-14 07:02 +0100
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-14 09:51 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 00:43 +0800
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-14 18:14 +0100
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 01:33 +0800
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-14 18:49 +0100
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 02:01 +0800
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-14 19:38 +0100
Re: How to write a self-referencial TM? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-14 13:00 -0700
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-14 15:02 -0500
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-14 21:19 +0100
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-14 21:16 +0100
Re: How to write a self-referencial TM? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-14 13:49 -0700
Re: How to write a self-referencial TM? Mr Flibble <flibble@red-dwarf.jmc.corp> - 2025-05-14 21:13 +0000
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-15 10:24 +0300
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-14 22:28 +0100
Re: How to write a self-referencial TM? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-14 14:40 -0700
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-14 23:02 +0100
Re: How to write a self-referencial TM? Andy Walker <anw@cuboid.co.uk> - 2025-05-15 01:09 +0100
Re: How to write a self-referencial TM? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-05-14 17:19 -0700
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 09:38 +0800
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 09:58 +0800
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 10:11 +0800
Re: How to write a self-referencial TM? Ben Bacarisse <ben@bsb.me.uk> - 2025-05-15 00:55 +0100
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-15 10:17 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-14 12:24 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 01:39 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-14 12:45 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 02:13 +0800
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-15 01:53 +0800
Re: How to write a self-referencial TM? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2025-05-15 17:08 +0100
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-15 11:47 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-16 03:57 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-15 15:50 -0500
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-16 10:33 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 10:43 -0500
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-16 12:10 -0400
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-17 11:58 +0300
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-15 19:37 -0400
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-16 10:27 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 10:40 -0500
Re: How to write a self-referencial TM? "Fred. Zwarts" <F.Zwarts@HetNet.nl> - 2025-05-19 10:21 +0200
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-19 13:39 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-20 23:41 -0500
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-21 11:47 +0300
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-21 07:11 -0400
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-16 02:49 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-15 14:15 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-16 04:08 +0800
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-16 10:45 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 10:47 -0500
Re: How to write a self-referencial TM? "Fred. Zwarts" <F.Zwarts@HetNet.nl> - 2025-05-16 21:34 +0200
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-16 10:40 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 10:44 -0500
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-17 12:02 +0300
Re: How to write a self-referencial TM? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2025-05-16 01:40 +0100
Re: How to write a self-referencial TM? Richard Heathfield <rjh@cpax.org.uk> - 2025-05-16 01:59 +0100
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-16 09:47 +0800
Re: How to write a self-referencial TM? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2025-05-16 03:26 +0100
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-16 19:40 +0800
Re: How to write a self-referencial TM? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2025-05-16 16:33 +0100
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-17 03:35 +0800
Re: How to write a self-referencial TM? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2025-05-16 23:51 +0100
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-17 11:01 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 22:12 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-17 11:23 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 22:40 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-17 11:49 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 22:58 -0500
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-17 09:02 -0400
Re: How to write a self-referencial TM? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2025-05-17 15:45 +0100
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-18 03:26 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-17 14:39 -0500
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-18 11:20 +0300
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-19 04:35 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-18 15:57 -0500
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-18 17:45 -0400
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-19 05:46 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-18 17:09 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-19 06:35 +0800
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-18 19:09 -0400
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-19 07:54 +0800
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-19 13:52 +0300
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-19 13:48 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-20 23:36 -0500
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-21 11:56 +0300
Re: How to write a self-referencial TM? André G. Isaak <agisaak@gm.invalid> - 2025-05-18 15:58 -0600
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-18 17:08 -0500
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-18 19:19 -0400
Re: How to write a self-referencial TM? André G. Isaak <agisaak@gm.invalid> - 2025-05-18 21:21 -0600
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-18 23:07 -0500
Re: How to write a self-referencial TM? "Fred. Zwarts" <F.Zwarts@HetNet.nl> - 2025-05-19 09:54 +0200
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-19 15:29 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-20 23:33 -0500
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-21 12:03 +0300
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-21 07:16 -0400
Re: How to write a self-referencial TM? "Fred. Zwarts" <F.Zwarts@HetNet.nl> - 2025-05-21 21:43 +0200
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-21 14:49 -0500
Re: How to write a self-referencial TM? "Fred. Zwarts" <F.Zwarts@HetNet.nl> - 2025-05-23 13:03 +0200
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-19 13:44 +0300
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-19 13:41 +0300
Re: How to write a self-referencial TM? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2025-05-17 20:46 +0100
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-17 14:55 -0500
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-17 16:07 -0400
Re: How to write a self-referencial TM? Andy Walker <anw@cuboid.co.uk> - 2025-05-16 12:22 +0100
Re: How to write a self-referencial TM? Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2025-05-16 16:57 +0100
Re: How to write a self-referencial TM? Andy Walker <anw@cuboid.co.uk> - 2025-05-16 21:04 +0100
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 15:38 -0500
Re: How to write a self-referencial TM? wij <wyniijj5@gmail.com> - 2025-05-17 05:21 +0800
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 16:40 -0500
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-16 20:32 -0400
Re: How to write a self-referencial TM? Richard Damon <richard@damon-family.org> - 2025-05-16 17:59 -0400
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-16 10:24 +0300
Re: How to write a self-referencial TM? olcott <polcott333@gmail.com> - 2025-05-16 10:37 -0500
Re: How to write a self-referencial TM? Mikko <mikko.levanto@iki.fi> - 2025-05-15 10:07 +0300
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