Extracting randomness: how and why. A survey

Extractors are Boolean functions that allow, in some precise sense, extraction of randomness from somewhat random distributions. Extractors, and the closely related “Dispersers”, exhibit some of the most “random-like” properties of explicitly constructed combinatorial structures. In turn, extractors and dispersers have many applications in “removing randomness” in various settings and in making randomized constructions explicit. This manuscript surveys extractors and dispersers: what they are, how they can be designed, and some of their applications. The work described is due to of a long list of research papers by various authors-most notably by David Zuckerman