Fast Lp-Based Approximations For Geometric Packing And Covering Problems

We derive fast approximation schemes for LP relaxations of several well-studied geometric optimization problems that include packing, covering, and mixed packing and covering constraints. Previous work in computational geometry concentrated mainly on the rounding stage to prove approximation bounds, assuming that the underlying LPs can be solved efficiently. This work demonstrates that many of those results can be made to run in nearly linear time. In contrast to prior work on this topic our algorithms handle weights and capacities, side constraints, and also apply to mixed packing and covering problems, in a unified fashion. Our framework relies crucially on the properties of a randomized MWU algorithm of [41]; we demonstrate that it is well-suited for range spaces that admit efficient approximate dynamic data structures for emptiness oracles. Our framework cleanly separates the MWU algorithm for solving the LP from the key geometric data structure primitives, and this enables us to handle side constraints in a simple way. Combined with rounding algorithms that can also be implemented efficiently, we obtain the first near-linear constant factor approximation algorithms for several problems.