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Groups > comp.lang.c > #89559

Re: [sOT] compression 1 GB downto 100 MB

From Keith Thompson <kst-u@mib.org>
Newsgroups comp.lang.c
Subject Re: [sOT] compression 1 GB downto 100 MB
Date 2016-06-18 13:22 -0700
Organization None to speak of
Message-ID <lnr3bus0v0.fsf@kst-u.example.com> (permalink)
References (4 earlier) <6f9b9b25-8347-4cbc-a23a-9e6c273bf6d2@googlegroups.com> <nk3503$7v0$1@dont-email.me> <be950b83-2eab-48aa-9616-ccc2174bf61c@googlegroups.com> <nk46d0$3oa$1@dont-email.me> <nk488q$94m$2@dont-email.me>

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Richard Heathfield <rjh@cpax.org.uk> writes:
> On 18/06/16 20:11, Bill Cunningham wrote:
> <snip>
>>
>>      Truely random can't be compressed?
>
> Right.
>
>> If there's a header indicating the
>> algorithm of randomness,  or encryption why not?
>
> If you can generate it via an algorithm, it isn't truly random.

Right.  If a sequence is truly random, then there is no way, given the
first N-1 bits of the sequence to predict the N'th bit with better than
50% accuracy.

There are pseudo-random sequences that can't *practically* be
compressed, because the compression algorithm will be unable to detect
the algorithm and parameters that went into it.  You can compress the
first million digits of pi in base 10 to the string "the first million
digits of pi in base 10", but only if your algorithm recognizes it (and
at the cost of not being able to use that particular string to represent
any other sequence).

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

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Thread

[sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-16 07:25 -0700
  Re: [sOT] compression 1 GB downto 100 MB mark.bluemel@gmail.com - 2016-06-16 08:08 -0700
    Re: [sOT] compression 1 GB downto 100 MB Lynn McGuire <lmc@winsim.com> - 2016-06-17 12:04 -0500
      Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-17 10:16 -0700
        Re: [sOT] compression 1 GB downto 100 MB "Chris M. Thomasson" <nospam@nospam.invalid> - 2016-06-17 23:08 -0700
  Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-16 08:09 -0700
    Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-16 08:15 -0700
      Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-16 08:18 -0700
        Re: [sOT] compression 1 GB downto 100 MB mark.bluemel@gmail.com - 2016-06-17 01:28 -0700
          Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-17 02:03 -0700
            Re: [sOT] compression 1 GB downto 100 MB Richard Heathfield <rjh@cpax.org.uk> - 2016-06-17 10:34 +0100
              Re: [sOT] compression 1 GB downto 100 MB BartC <bc@freeuk.com> - 2016-06-17 10:44 +0100
                Re: [sOT] compression 1 GB downto 100 MB Richard Heathfield <rjh@cpax.org.uk> - 2016-06-17 11:03 +0100
                Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-17 03:51 -0700
                Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-18 02:16 -0700
                Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-18 02:29 -0700
                Re: [sOT] compression 1 GB downto 100 MB "Osmium" <r124c4u102@comcast.net> - 2016-06-17 08:19 -0500
                Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-18 03:17 -0700
              Re: [sOT] compression 1 GB downto 100 MB Gareth Owen <gwowen@gmail.com> - 2016-06-17 18:32 +0100
      Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-16 08:43 -0700
        Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-16 08:48 -0700
      Re: [sOT] compression 1 GB downto 100 MB "Osmium" <r124c4u102@comcast.net> - 2016-06-16 10:49 -0500
        Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-16 09:10 -0700
          Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-16 09:36 -0700
            Re: [sOT] compression 1 GB downto 100 MB Keith Thompson <kst-u@mib.org> - 2016-06-16 11:18 -0700
          Re: [sOT] compression 1 GB downto 100 MB "Osmium" <r124c4u102@comcast.net> - 2016-06-16 13:13 -0500
            Re: [sOT] compression 1 GB downto 100 MB Gareth Owen <gwowen@gmail.com> - 2016-06-16 20:18 +0100
              Re: [sOT] compression 1 GB downto 100 MB Richard Heathfield <rjh@cpax.org.uk> - 2016-06-16 22:07 +0100
                Re: [sOT] compression 1 GB downto 100 MB Gareth Owen <gwowen@gmail.com> - 2016-06-17 06:04 +0100
              Re: [sOT] compression 1 GB downto 100 MB Robert Wessel <robertwessel2@yahoo.com> - 2016-06-16 23:21 -0500
                Re: [sOT] compression 1 GB downto 100 MB "Osmium" <r124c4u102@comcast.net> - 2016-06-17 07:49 -0500
                Re: [sOT] compression 1 GB downto 100 MB Robert Wessel <robertwessel2@yahoo.com> - 2016-06-17 12:47 -0500
                Re: [sOT] compression 1 GB downto 100 MB "Osmium" <r124c4u102@comcast.net> - 2016-06-17 14:47 -0500
                Re: [sOT] compression 1 GB downto 100 MB Robert Wessel <robertwessel2@yahoo.com> - 2016-06-17 23:32 -0500
                Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-18 01:33 -0700
            Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-17 14:51 -0700
      Re: [sOT] compression 1 GB downto 100 MB BartC <bc@freeuk.com> - 2016-06-16 16:50 +0100
        Re: [sOT] compression 1 GB downto 100 MB BartC <bc@freeuk.com> - 2016-06-17 16:20 +0100
    Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-16 08:34 -0700
  Re: [sOT] compression 1 GB downto 100 MB Les Cargill <lcargill99@comcast.com> - 2016-06-16 12:55 -0500
  Re: [sOT] compression 1 GB downto 100 MB "Chris M. Thomasson" <nospam@nospam.invalid> - 2016-06-16 11:53 -0700
    Re: [sOT] compression 1 GB downto 100 MB "Chris M. Thomasson" <nospam@nospam.invalid> - 2016-06-16 12:14 -0700
    Re: [sOT] compression 1 GB downto 100 MB "Chris M. Thomasson" <nospam@nospam.invalid> - 2016-06-17 12:33 -0700
      Re: [sOT] compression 1 GB downto 100 MB "Chris M. Thomasson" <nospam@nospam.invalid> - 2016-06-17 12:46 -0700
    Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-17 15:04 -0700
      Re: [sOT] compression 1 GB downto 100 MB "Chris M. Thomasson" <nospam@nospam.invalid> - 2016-06-17 22:55 -0700
        Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-18 01:38 -0700
          Re: [sOT] compression 1 GB downto 100 MB BartC <bc@freeuk.com> - 2016-06-18 10:41 +0100
            Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-18 02:55 -0700
            Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-18 05:08 -0700
              Re: [sOT] compression 1 GB downto 100 MB "Bill Cunningham" <nospam@nspam.invalid> - 2016-06-18 15:11 -0400
                Re: [sOT] compression 1 GB downto 100 MB "Bill Cunningham" <nospam@nspam.invalid> - 2016-06-18 15:13 -0400
                Re: [sOT] compression 1 GB downto 100 MB luser droog <luser.droog@gmail.com> - 2016-06-18 12:43 -0700
                Re: [sOT] compression 1 GB downto 100 MB Richard Heathfield <rjh@cpax.org.uk> - 2016-06-18 20:43 +0100
                Re: [sOT] compression 1 GB downto 100 MB "Chris M. Thomasson" <nospam@nospam.invalid> - 2016-06-18 12:53 -0700
                Re: [sOT] compression 1 GB downto 100 MB "Chris M. Thomasson" <nospam@nospam.invalid> - 2016-06-20 20:32 -0700
                Re: [sOT] compression 1 GB downto 100 MB Keith Thompson <kst-u@mib.org> - 2016-06-18 13:22 -0700
                Re: [sOT] compression 1 GB downto 100 MB Jerry Stuckle <jstucklex@attglobal.net> - 2016-06-18 16:35 -0400
                Re: [sOT] compression 1 GB downto 100 MB Jerry Stuckle <jstucklex@attglobal.net> - 2016-06-18 21:37 -0400
                Re: [sOT] compression 1 GB downto 100 MB "James R. Kuyper" <jameskuyper@verizon.net> - 2016-06-18 16:59 -0400
                Re: [sOT] compression 1 GB downto 100 MB crisdunbar@gmail.com - 2016-06-20 09:55 -0700
                Re: [sOT] compression 1 GB downto 100 MB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-06-20 21:22 +0100
                Re: [sOT] compression 1 GB downto 100 MB cris <crisdunbar@gmail.com> - 2016-06-20 17:13 -0700
                Re: [sOT] compression 1 GB downto 100 MB Tim Rentsch <txr@alumni.caltech.edu> - 2016-06-21 10:42 -0700
                Re: [sOT] compression 1 GB downto 100 MB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-06-21 20:09 +0100
                Re: [sOT] compression 1 GB downto 100 MB crisdunbar@gmail.com - 2016-06-21 13:39 -0700
                Re: [sOT] compression 1 GB downto 100 MB Keith Thompson <kst-u@mib.org> - 2016-06-22 08:34 -0700
                Re: [sOT] compression 1 GB downto 100 MB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-06-22 19:48 +0100
                Re: [sOT] compression 1 GB downto 100 MB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-06-19 01:37 +0100
                Re: [sOT] compression 1 GB downto 100 MB Richard Heathfield <rjh@cpax.org.uk> - 2016-06-19 02:22 +0100
                Re: [sOT] compression 1 GB downto 100 MB Jerry Stuckle <jstucklex@attglobal.net> - 2016-06-18 21:30 -0400
                Re: [sOT] compression 1 GB downto 100 MB Richard Heathfield <rjh@cpax.org.uk> - 2016-06-19 02:41 +0100
                Re: [sOT] compression 1 GB downto 100 MB Jerry Stuckle <jstucklex@attglobal.net> - 2016-06-18 21:55 -0400
                Re: [sOT] compression 1 GB downto 100 MB Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-06-19 03:20 +0100
                Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-19 02:53 -0700
                Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-18 16:05 -0700
                Re: [sOT] compression 1 GB downto 100 MB "J. Clarke" <j.clarke.873638@gmail.com> - 2016-06-19 06:59 -0400
                Re: [sOT] compression 1 GB downto 100 MB fir <profesor.fir@gmail.com> - 2016-06-19 05:55 -0700
                Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-19 06:13 -0700
                Re: [sOT] compression 1 GB downto 100 MB "J. Clarke" <j.clarke.873638@gmail.com> - 2016-06-26 12:26 -0400
                Re: [sOT] compression 1 GB downto 100 MB Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-06-26 09:53 -0700
              Re: [sOT] compression 1 GB downto 100 MB Richard Heathfield <rjh@cpax.org.uk> - 2016-06-18 20:41 +0100
              Re: [sOT] compression 1 GB downto 100 MB "J. Clarke" <j.clarke.873638@gmail.com> - 2016-06-19 06:45 -0400
            Re: [sOT] compression 1 GB downto 100 MB Robert Wessel <robertwessel2@yahoo.com> - 2016-06-18 14:42 -0500
            Re: [sOT] compression 1 GB downto 100 MB gordonb.vnsk1@burditt.org (Gordon Burditt) - 2016-06-20 01:13 -0500
              Re: [sOT] compression 1 GB downto 100 MB Keith Thompson <kst-u@mib.org> - 2016-06-20 12:16 -0700
                Re: [sOT] compression 1 GB downto 100 MB David Brown <david.brown@hesbynett.no> - 2016-06-20 21:27 +0200
                Re: [sOT] compression 1 GB downto 100 MB Xaltonon <xaltonon@gmail.com> - 2016-06-20 21:25 -0700

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