Approximation and Complexity of k-Splittable Flows

Given a graph with a source and a sink node, the NP–hard maximum k–splittable flow (MkSF) problem is to find a flow of maximum value with a flow decomposition using at most k paths [6]. The multicommodity variant of this problem is a natural generalization of disjoint paths and unsplittable flow problems. Constructing a k–splittable flow requires two interdepending decisions. One has to decide on k paths (routing) and on the flow values on these paths (packing). We give efficient algorithms for computing exact and approximate solutions by decoupling the two decisions into a first packing step and a second routing step. Our main contributions are as follows: (i) We show that for constant k a polynomial number of packing alternatives containing at least one packing used by an optimal MkSF solution can be constructed in polynomial time. If k is part of the input, we obtain a slightly weaker result. In this case we can guarantee that, for any fixed > 0, the computed set o...

• Type: Conference
• Year: 2005
• Where: WAOA
• Authors: Ronald Koch, Martin Skutella, Ines Spenke
• Keywords: K–splittable flow, Polynomial Time, WAOA 2005, flow Values