On the Structure and Complexity of the 2-Connected Steiner Network Problem in the Plane

Emily L. Luebke and J. Scott Provan, Department of Operations Research, University of North Carolina
 

Abstract

We consider the problem of finding a minimum Euclidean length graph 2-connecting a set of points in the plane.  We show that the solution to this problem is an edge-disjoint union of full Steiner trees.  This has three important corollaries.  The first is a proof that the problem is NP-hard --- even in the sense of finding a fully polynomial approximation scheme.  The second is a complete description of the solutions for 2SNPP for rectangular arrays of lattice points.  The third is a linear-time algorithm for constructing an optimal solution to 2SNPP given its topological description.