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399 points seanhunter | 3 comments | | HN request time: 0.401s | source
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NameError ◴[] No.42184405[source]
Easy way to get a fair result from an unfair coin toss: Flip the coin twice in a row, in this case starting with the same side facing up both times, so it's equally unfair for both tosses. If you get heads-heads or tails-tails, discard and start over until you get either heads-tails or tails-heads, which have equal probabilities (so you can say something like HT = "heads" and TH = "tails").

This works even if the coin lands heads 99% of the time, as long as it's consistent (but you'll probably have to flip a bunch of times in that case).

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1. simcop2387 ◴[] No.42184577[source]
If anyone wants to look up why this might work, it's a Whitening transform [0]. I can't find the name of the algorithm itself being describe in the parent but there's more than just that for accomplishing the same thing.

0: https://en.wikipedia.org/wiki/Whitening_transformation

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2. npsomaratna ◴[] No.42185097[source]
Thank you. This was useful to learn.
3. aidenn0 ◴[] No.42188994[source]
That's Von Neumann Whitening.