
Getting a Fair Toss From a Biased Coin - spydez
http://www.billthelizard.com/2009/09/getting-fair-toss-from-biased-coin.html
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vegashacker
von Neumann is credited with coming up with the fair toss trick:

[http://en.wikipedia.org/wiki/Fair_coin#Fair_results_from_a_b...](http://en.wikipedia.org/wiki/Fair_coin#Fair_results_from_a_biased_coin)

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cruise02
Thanks, I didn't know who originated that method. I added a note citing von
Neumann.

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joshu
Flip the coin to get sufficient entropy, then take the md5 of the bits
generated. That should give you some number of virtual flips as output.

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defen
Since you can't end up with more entropy than you started with by using a
deterministic process, if you're going to do that you may as well use the bits
to seed a random number generator.

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JulianMorrison
Haha! I saw the title and thought "how would I..." and reinvented it in
seconds, almost (mine differed in that I'd allocate the H or T value of each
pair arbitrarily by fiat ahead of time).

Edit: oops! I failed to reinvent discarding by pairs. That makes my attempt a
fail. D'oh!

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roundsquare
Neat idea. But how do you convince your friends to do this?

A: I call heads.

<flip>

B: It came up tails! I win!

A: No, wait, we're not done yet. We need to flip it again, if it comes up
tails, we start over.

B: What? No, give me my doughnut!

