Capacitated Sum-Of-Radii Clustering: An FPT Approximation

Authors Tanmay Inamdar, Kasturi Varadarajan

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Tanmay Inamdar
  • Department of Computer Science, University of Iowa, Iowa City, IA, USA
Kasturi Varadarajan
  • Department of Computer Science, University of Iowa, Iowa City, IA, USA

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Tanmay Inamdar and Kasturi Varadarajan. Capacitated Sum-Of-Radii Clustering: An FPT Approximation. In 28th Annual European Symposium on Algorithms (ESA 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 173, pp. 62:1-62:17, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


In sum of radii clustering, the input consists of a finite set of points in a metric space. The problem asks to place a set of k balls centered at a subset of the points such that every point is covered by some ball, and the objective is to minimize the sum of radii of these balls. In the capacitated version of the problem, we want to assign each point to a ball containing it, such that no ball is assigned more than U points, where U denotes the capacity of the points. While constant approximations are known for the uncapacitated version of the problem, there is no work on the capacitated version. We make progress on this problem by obtaining a constant approximation using a Fixed Parameter Tractable (FPT) algorithm. In particular, the running time of the algorithm is of the form 2^O(k²) ⋅ n^O(1). As a warm-up for this result, we also give a constant approximation for the uncapacitated sum of radii clustering problem with matroid constraints, thus obtaining the first FPT approximation for this problem.

Subject Classification

ACM Subject Classification
  • Theory of computation → Facility location and clustering
  • Sum-of-radii Clustering
  • Capacitated Clustering


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