We present a very simple and efficient sampling-based algorithm for estimating the union of sets in the streaming setting. Suppose we have a collection of sets S_1, . . .

In any tournament between several participants, transitivity is sometimes not satisfied (i.e. A may defeat B, B defeats C and C in turn defeats A). In any case, we shall have to define a winner.

Quantum computers are in general believed to be more powerful than classical computers, but it is not clear if they are powerful enough to solve problems that a classical computer can’t even verify.

We introduce the problem of determining the identity of a byzantine user (internal adversary) in a communication system.