==Graph theory== An (``N``, ``M``, ``D``, ``K``, ``e``)-disperser is a bipartite graph with N vertices on the left side, each with degree D, and M vertices on the right side, such that every subset of K vertices on the left side is connected to more than (1 − e)M vertices on the right. An extractor is a related type of graph ... Found on http://en.wikipedia.org/wiki/Disperser