46 : 2 Incremental Exact Min - Cut in Poly - logarithmic Amortized

We present a deterministic incremental algorithm for exactly maintaining the size of a minimum cut with Õ(1) amortized time per edge insertion and O(1) query time. This result partially answers an open question posed by Thorup [Combinatorica 2007]. It also stays in sharp contrast to a polynomial conditional lower-bound for the fully-dynamic weighted minimum cut problem. Our algorithm is obtained by combining a recent sparsification technique of Kawarabayashi and Thorup [STOC 2015] and an exact incremental algorithm of Henzinger [J. of Algorithm 1997]. We also study space-efficient incremental algorithms for the minimum cut problem. Concretely, we show that there exists an O(n logn/ε2) space Monte-Carlo algorithm that can process a stream of edge insertions starting from an empty graph, and with high probability, the algorithm maintains a (1 + ε)-approximation to the minimum cut. The algorithm has Õ(1) amortized update-time and constant query-time. 1998 ACM Subject Classification G.2.2 Graph Theory