Disperser

A disperser is a one-sided extractor. Where an extractor requires that every event gets the same probability under the uniform distribution and the extracted distribution, only the latter is required for a disperser. So for a disperser, an event we have:

Definition (Disperser): A -disperser is a function

such that for every distribution on with the support of the distribution is of size at least .

Read more about Disperser:  Graph Theory, Other Meanings