Approximation, Randomization, and Combinatorial Optimization. Algorithms and Techniques : 9th International Workshop on Approximation Algorithms for Combinatorial Optimization Problems, APPROX 2006 and 10th International Workshop on Randomization and Computation, RANDOM 2006, Barcelona, Spain, August 28-30, 2006, Proceedings - Josep Díaz, Klaus Jansen, José D. P. Rolim, Uri Zwick ((Lecture Notes in Computer Science))