A Subquadratic Time Approximation Algorithm for Individually Fair k-Center

Fuente: arXiv
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Auteurs principaux: Ebbens, Matthijs, Funk, Nicole, Höckendorff, Jan, Sohler, Christian, Weil, Vera
Format: Preprint
Publié: 2024
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author Ebbens, Matthijs
Funk, Nicole
Höckendorff, Jan
Sohler, Christian
Weil, Vera
author_facet Ebbens, Matthijs
Funk, Nicole
Höckendorff, Jan
Sohler, Christian
Weil, Vera
contents We study the $k$-center problem in the context of individual fairness. Let $P$ be a set of $n$ points in a metric space and $r_x$ be the distance between $x \in P$ and its $\lceil n/k \rceil$-th nearest neighbor. The problem asks to optimize the $k$-center objective under the constraint that, for every point $x$, there is a center within distance $r_x$. We give bicriteria $(β,γ)$-approximation algorithms that compute clusterings such that every point $x \in P$ has a center within distance $βr_x$ and the clustering cost is at most $γ$ times the optimal cost. Our main contributions are a deterministic $O(n^2+ kn \log n)$ time $(2,2)$-approximation algorithm and a randomized $O(nk\log(n/δ)+k^2/\varepsilon)$ time $(10,2+\varepsilon)$-approximation algorithm, where $δ$ denotes the failure probability. For the latter, we develop a randomized sampling procedure to compute constant factor approximations for the values $r_x$ for all $x\in P$ in subquadratic time; we believe this procedure to be of independent interest within the context of individual fairness.
format Preprint
id arxiv_https___arxiv_org_abs_2412_04943
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Subquadratic Time Approximation Algorithm for Individually Fair k-Center
Ebbens, Matthijs
Funk, Nicole
Höckendorff, Jan
Sohler, Christian
Weil, Vera
Data Structures and Algorithms
Computational Geometry
We study the $k$-center problem in the context of individual fairness. Let $P$ be a set of $n$ points in a metric space and $r_x$ be the distance between $x \in P$ and its $\lceil n/k \rceil$-th nearest neighbor. The problem asks to optimize the $k$-center objective under the constraint that, for every point $x$, there is a center within distance $r_x$. We give bicriteria $(β,γ)$-approximation algorithms that compute clusterings such that every point $x \in P$ has a center within distance $βr_x$ and the clustering cost is at most $γ$ times the optimal cost. Our main contributions are a deterministic $O(n^2+ kn \log n)$ time $(2,2)$-approximation algorithm and a randomized $O(nk\log(n/δ)+k^2/\varepsilon)$ time $(10,2+\varepsilon)$-approximation algorithm, where $δ$ denotes the failure probability. For the latter, we develop a randomized sampling procedure to compute constant factor approximations for the values $r_x$ for all $x\in P$ in subquadratic time; we believe this procedure to be of independent interest within the context of individual fairness.
title A Subquadratic Time Approximation Algorithm for Individually Fair k-Center
topic Data Structures and Algorithms
Computational Geometry
url https://arxiv.org/abs/2412.04943