Improved approximation algorithms for solving the squared metric k-facility location problem.

The squared metric k -facility location problem is a frequently encountered generalization of the k -means problem, where a specific cost should be paid for opening each facility. The current best approximation ratio for this problem is 44.473 + ϵ , which was obtained using a local search algorithm. We advance the state-of-the-art for the problem by devising a Lagrangian relaxation-based algorithm that achieves an improved approximation guarantee of 36.342 + ϵ. Our improvement comes from a new deterministic rounding approach, which exploits the properties of the squared metric. • We give a (36.342 + ϵ) -approximation algorithm for the squared metric k -facility location problem. • We obtain a well-behaved fractional solution to the squared metric k -facility location problem based on the framework of Lagrangian relaxation. • We give a new deterministic rounding approach that exploits the properties of the squared metric. [ABSTRACT FROM AUTHOR]