Approximation algorithms for facility location problems (extended abstract)
STOC '97 Proceedings of the twenty-ninth annual ACM symposium on Theory of computing
A polylogarithmic approximation algorithm for the group Steiner tree problem
Proceedings of the ninth annual ACM-SIAM symposium on Discrete algorithms
A 3-approximation algorithm for the k-level uncapacitated facility location problem
Information Processing Letters
An Improved Approximation Algorithm for the Metric Uncapacitated Facility Location Problem
Proceedings of the 9th International IPCO Conference on Integer Programming and Combinatorial Optimization
Improved Approximation Algorithms for the Uncapacitated Facility Location Problem
SIAM Journal on Computing
Approximating the two-level facility location problem via a quasi-greedy approach
SODA '04 Proceedings of the fifteenth annual ACM-SIAM symposium on Discrete algorithms
Improved Combinatorial Approximation Algorithms for the k-Level Facility Location Problem
SIAM Journal on Discrete Mathematics
An Optimal Bifactor Approximation Algorithm for the Metric Uncapacitated Facility Location Problem
SIAM Journal on Computing
A 1.488 approximation algorithm for the uncapacitated facility location problem
ICALP'11 Proceedings of the 38th international conference on Automata, languages and programming - Volume Part II
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We study the k-level uncapacitated facility location problem, where clients need to be connected with paths crossing open facilities of k types (levels). In this paper we give an approximation algorithm that for any constant k, in polynomial time, delivers solutions of cost at most αk times OPT, where αk is an increasing function of k, with limk→∞αk=3. Our algorithm rounds a fractional solution to an extended LP formulation of the problem. The rounding builds upon the technique of iteratively rounding fractional solutions on trees (Garg, Konjevod, and Ravi SODA'98) originally used for the group Steiner tree problem. We improve the approximation ratio for k-UFL for all k≥3, in particular we obtain the ratio equal 2.02, 2.14, and 2.24 for k=3,4, and 5.