In all the talk of super computers there is not...

Leichter, Jerry leichter_jerrold at
Thu Sep 6 09:28:40 EDT 2007

| Hi Martin,
| I did forget to say that it would be salted so that throws it off by
| 2^12
| A couple of questions. How did you come up with the ~2.5 bits per
| word? Would a longer word have more bits?
He misapplied an incorrect estimate!  :-) The usual estimate - going
back to Shannon's original papers on information theory, actually - is
that natural English text has about 2.5 (I think it's usually given as
2.4) bits of entropy per *character*.  There are several problems here:

	- The major one is that the estimate should be for *characters*,
		not *words*.  So the number of bits of entropy in
		a 55-character phrase is about 137 (132, if you use
		2.4 bits/character), not 30.

	- The minor one is that the English entropy estimate looks just
		at letters and spaces, not punctuation and capitalization.
		So it's probably low anyway.  However, this is a much
		smaller effect.

							-- Jerry

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