Can someone post what they consider to be a truly random, absolutely uncompressable file? (I''m continuing from the closed fluke compression thread.) It must be at least 96 bits. ''cause I took what I considered to be completely random, and I got 5 bits out of it (over 5%). It had equal 1''s and 0''s and equal numbers of patterns of three bits. Thanks.
Lack
Christianity, Creation, metric, Dvorak, and BeOS for all!

why would you want that?

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blah blah blah

- pouya

To see if I can compress it. Everyone says you can''t. But they also said that if you take all files of a certain size and add up savings or losses that you get using a particular algorithm, you always lose out by at least one bit. That turned out to be false.


Lack

Christianity, Creation, metric, Dvorak, and BeOS for all!

Well, if you can compress random data over and over again, why don''t you try compressing a 1 meg file into 100 bits?

Anyway, you could try using encrypted data as a random bitstream since one of the properties of strong cryptography is that it produces random-looking (statisticly) ciphertext. Just encrypt a file with PGP and remove the headers, then try to compress the rest... or something.

Henry

why dont you just compress a file 2 or 3 times with something like winzip (to make sure that it''s not gonna be able to compress anymore) and then try your progrma with it?

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"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us"
- pouya

Because 1) It''s not a program, I''m doing it on paper, 2) Someone already gave me part of a file, and it wasn''t random (they said the whole file would be) 3) I''m inexperienced at bitwise programming and file handling.

If someone would just post an original ~100 bit stream that they feel could not be compressed.


Lack

Christianity, Creation, metric, Dvorak, and BeOS for all!

the word "uncompressable"
that''s 14*8 = 112 bits, happy?

- pouya
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"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us"

Lack, you missed the point.

It isn''t that certain files cannot be compressed, it''s that no compression algorithm can compress all files.

For example, there is no compression algorithm that can compress *all* of the following streams losslessly by even a bit:

000
001
010
011
100
101
110
111

Granted, they''re tiny 3 bit streams, but the same idea applies no matter how long of a bitstream you look at.

Jesse Chounard

I only know a few methods like LZW compression.

If someone gives me a bit stream and calls it uncompressable, I just laugh. I just let 0 = 01010100010101... (the bit stream), send the 0, and then decode at the other end. Ahh, the dictionary method Of course I had a lot of knowledge beforehand.

I know, but one of the things they said is that ''truely random data cannot be compressed.''

Anyhow, then what''s with that $5000 contest? If the guy sends you the file, you could create a specific algorithm for it and win $5000, no?


Lack

Christianity, Creation, metric, Dvorak, and BeOS for all!