# Independent Unbiased Coin Flips From a Correlated Biased Source: a Finite State Markov Chain

@inproceedings{Blum1984IndependentUC, title={Independent Unbiased Coin Flips From a Correlated Biased Source: a Finite State Markov Chain}, author={Manuel Blum}, booktitle={IEEE Annual Symposium on Foundations of Computer Science}, year={1984} }

von Neumann's trick for generating an absolutely unbiased coin from a biased one is this: 1. Toss the biased coin twice, getting 00, 01, 10, or 11. 2. If 00 or 11 occur, go back to step 1; else 3. Call 10 a H, 01 a T. Since p[H] = p[1]*p[0] = p[T], the output is unbiased. Example: 00 10 11 01 01 /spl I.oarr/ H T T. Peter Elias gives an algorithm to generate an independent unbiased sequence of Hs and Ts that nearly achieves the Entropy of the one-coin source. His algorithm is excellent, but…

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