Improving Spanning Trees by Upgrading Nodes

Sven Oliver Krumke, Madhav V. Marathe, Hartmut Noltemeier, R. Ravi, S. S. Ravi, Ravi Sundaram, Hans-Christoph Wirth

Abstract: We study budget constrained optimal network upgrading problems. We are given an edge weighted graph G=(V, E) where node υ ∈ V can be upgraded at a cost of c(υ). This upgrade reduces the delay of each link emanating from υ. The goal is to find a minimum cost set of nodes to be upgraded so that the resulting network has a good performance. We consider two performance measures, namely, the weight of a minimum spanning tree and the bottleneck weight of a minimum bottleneck spanning tree, and present approximation algorithms.