Network construction with subgraph connectivity constraints

• Published in: Journal of combinatorial optimization Vol. 29; no. 2; pp. 418 - 432
• Main Authors: Angluin, Dana, Aspnes, James, Reyzin, Lev
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.02.2015
• Subjects: Combinatorics; Convex and Discrete Geometry; Mathematical Modeling and Industrial Mathematics; Mathematics; Mathematics and Statistics; Operations Research/Decision Theory; Optimization; Theory of Computation; Connectivity; Network optimization; Subgraph constraints
• ISSN: 1382-6905; 1573-2886
• DOI: 10.1007/s10878-013-9603-2

We consider the problem introduced by Korach and Stern (Mathematical Programming, 98:345–414, 2003 ) of building a network given connectivity constraints. A network designer is given a set of vertices and constraints , and seeks to build the lowest cost set of edges such that each induces a connected subgraph of . First, we answer a question posed by Korach and Stern (Discrete Applied Mathematics, 156:444–450, 2008 ): for the offline version of the problem, we prove an hardness of approximation result for uniform cost networks (where edge costs are all ) and give an algorithm that almost matches this bound, even in the arbitrary cost case. Then we consider the online problem, where the constraints must be satisfied as they arrive. We give an -competitive algorithm for the arbitrary cost online problem, which has an -competitive lower bound. We look at the uniform cost case as well and give an -competitive algorithm against an oblivious adversary, as well as an -competitive lower bound against an adaptive adversary. We also examine cases when the underlying network graph is known to be a star or a path and prove matching upper and lower bounds of on the competitive ratio for them.