Maximum Matching in Turnstile Streams

We consider the unweighted bipartite maximum matching problem in the one-pass turnstile streaming model where the input stream consists of edge insertions and deletions. In the insertion-only model, a one-pass 2-approximation streaming algorithm can be easily obtained with space O(n log n), where n denotes the number of vertices of the input graph. We show that no such result is possible if edge deletions are allowed, even if space O(n(3/2-delta)) is granted, for every delta > 0. Specifically, for every 0 <= epsilon <= 1, we show that in the one-pass turnstile streaming model, in order to compute (O) over tilde (n(epsilon))-approximation, space Omega(n(3/2-4 epsilon)) is required for constant error randomized algorithms, and, up to logarithmic factors, space Omega(O) over tilde (n(2-2 epsilon)) is sufficient. Our lower bound result is proved in the simultaneous message model of communication and may be of independent interest.