A 1.5-Approximation of the Minimal Manhattan Network Problem

Given a set of points in the plane, the Minimal Manhattan Network Problem asks for an axis-parallel network that connects every pair of points by a shortest path under L1-norm (Manhattan metric). The goal is to minimize the overall length of the network. We present an approximation algorithm that provides a solution of length at most 1.5 times the optimum. Previously, the best known algorithm has given only a 2-approximation.