@article {17595,
	title = {Explicit OR-dispersers with polylogarithmic degree},
	journal = {Journal of the ACM (JACM)},
	volume = {45},
	year = {1998},
	month = {1998/01//},
	pages = {123 - 154},
	abstract = {An (N, M, T)-OR-disperser is a bipartite multigraph G=(V, W, E) with |V| = N, and |W| = M, having the following expansion property: any subset of V having at least T vertices has a neighbor set of size at least M/2. For any pair of constants \&xgr;, \&lgr;, 1 >= \&xgr; > \&lgr; >= 0, any sufficiently large N, and for any T >= 2(logN) M <= 2(log N)\&lgr;, we give an explicit elementary construction of an (N, M,    T)-OR-disperser such that the out-degree of any vertex in V is at most polylogarithmic in N. Using this with known applications of OR-dispersers yields several results. First, our construction implies that the complexity class Strong-RP defined by Sipser, equals RP. Second, for any fixed \&eegr; > 0, we give the first polynomial-time simulation of RP algorithms using the output of any {\textquotedblleft}\&eegr;-minimally random{\textquotedblright} source. For any integral R > 0, such a source accepts a single request for an R-bit string and generates the string according to a distribution that assigns probability at most 2-R\&eegr; to any string. It is minimally random in the sense that  any weaker source is insufficient to do a black-box polynomial-time simulation of RP algorithms.},
	keywords = {derandomization, expander graphs, explicit constructions, hardness of approximation, hashing lemmas, imperfect sources of randomness, measures of information, pseudo-random generators, randomized computation, time-space tradeoffs},
	isbn = {0004-5411},
	doi = {10.1145/273865.273915},
	url = {http://doi.acm.org/10.1145/273865.273915},
	author = {Saks,Michael and Srinivasan, Aravind and Zhou,Shiyu}
}
