Question: Consider a network of l computers R1, R2, ...,Rl in which each computer is directly connected via a communication link to each other. Let k be a positive integer. Assume that each Ri possesses a set Si ⊆ {0, 1}n, where |Si| ≤ k for all i ∈ {1, 2, ...,l}. Design and analyze a randomized communication protocol for deciding whether or not l i=1 Si is empty. The communication complexity is measured as the number of bits communicated via all links between the l computers.