Abstract

The essence of the simplest buy-at-bulk network design problem is buying network capacity "wholesale " to guarantee connectivity from all network nodes to a certain central network switch. Capacity is sold with "volume discount": the more capacity is bought, the cheaper is the price per unit of bandwidth. We provide O(log 2 n) randomized approximation algorithm for the problem. This solves the open problem in [15]. The only previously known solutions were restricted to special cases (Euclidean graphs) [15]. We solve additional natural variations of the problem, such as multi-sink network design, as well as selective network design. These problems can be viewed as generalizations of the the Generalized Steiner Connectivity and Prize-collecting salesman (K-MST) problems. In the selective network design problem, some subset of k wells must be connected to the (single) refinery, so that the total cost is minimized. 1 Introduction 1.1 The basic problem Consider an oil company that wi...

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