Optimal lower bounds for universal relation, and for samplers and finding duplicates in streams
Abstract: Consider the following problem: we monitor a sequence of edgeinsertions and deletions in a graph on n vertices, so there are N = (n choose 2) possible edges (e.g. monitoring a stream of friend accepts/removals on Facebook). At any point someone may say "query()", at which point must output a random edge that exists in the graph at that time from a distribution that is statistically close to uniform. More specifically, with probability p our edge should come from a distribution close to uniform,…