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We study data clustering problems with $\ell_p$-norm objectives (e.g. $k$-Median and $k$-Means) in the context of individual fairness. The dataset consists of $n$ points, and we want to find $k$ centers such that (a) the objective is…

Data Structures and Algorithms · Computer Science 2021-06-24 Deeparnab Chakrabarty , Maryam Negahbani

Given a data set of size $n$ in $d'$-dimensional Euclidean space, the $k$-means problem asks for a set of $k$ points (called centers) so that the sum of the $\ell_2^2$-distances between points of a given data set of size $n$ and the set of…

Data Structures and Algorithms · Computer Science 2021-06-01 Anamay Chaturvedi , Matthew Jones , Huy L. Nguyen

We investigate the fine-grained complexity of approximating the classical $k$-median / $k$-means clustering problems in general metric spaces. We show how to improve the approximation factors to $(1+2/e+\varepsilon)$ and…

Data Structures and Algorithms · Computer Science 2019-04-30 Vincent Cohen-Addad , Anupam Gupta , Amit Kumar , Euiwoong Lee , Jason Li

The paper gives approximation algorithms for the k-medians and facility-location problems (both NP-hard). For k-medians, the algorithm returns a solution using at most ln(n+n/epsilon)k medians and having cost at most (1+epsilon) times the…

Data Structures and Algorithms · Computer Science 2015-06-02 Neal E. Young

The $k$-Facility Location problem is a generalization of the classical problems $k$-Median and Facility Location. The goal is to select a subset of at most $k$ facilities that minimizes the total cost of opened facilities and established…

Data Structures and Algorithms · Computer Science 2017-04-25 Jarosław Byrka , Krzysztof Fleszar , Bartosz Rybicki , Joachim Spoerhase

\textit{Clustering problems} often arise in the fields like data mining, machine learning etc. to group a collection of objects into similar groups with respect to a similarity (or dissimilarity) measure. Among the clustering problems,…

Computational Geometry · Computer Science 2015-12-10 Sayan Bandyapadhyay , Kasturi Varadarajan

We consider the $k$-clustering problem with $\ell_p$-norm cost, which includes $k$-median, $k$-means and $k$-center, under an individual notion of fairness proposed by Jung et al. [2020]: given a set of points $P$ of size $n$, a set of $k$…

Data Structures and Algorithms · Computer Science 2022-03-02 Ali Vakilian , Mustafa Yalçıner

In this paper, we consider two types of robust models of the $k$-median/$k$-means problems: the outlier-version ($k$-MedO/$k$-MeaO) and the penalty-version ($k$-MedP/$k$-MeaP), in which we can mark some points as outliers and discard them.…

Data Structures and Algorithms · Computer Science 2021-01-01 Yishui Wang , Rolf H. Möhring , Chenchen Wu , Dachuan Xu , Dongmei Zhang

We study the $k$-median with discounts problem, wherein we are given clients with non-negative discounts and seek to open at most $k$ facilities. The goal is to minimize the sum of distances from each client to its nearest open facility…

Data Structures and Algorithms · Computer Science 2021-11-19 Shichuan Deng

Since its introduction in 1957, Lloyd's algorithm for $k$-means clustering has been extensively studied and has undergone several improvements. While in its original form it does not guarantee any approximation factor at all, Arthur and…

Data Structures and Algorithms · Computer Science 2024-06-06 Theo Conrads , Lukas Drexler , Joshua Könen , Daniel R. Schmidt , Melanie Schmidt

We consider the popular $k$-means problem in $d$-dimensional Euclidean space. Recently Friggstad, Rezapour, Salavatipour [FOCS'16] and Cohen-Addad, Klein, Mathieu [FOCS'16] showed that the standard local search algorithm yields a…

Data Structures and Algorithms · Computer Science 2017-08-30 Vincent Cohen-Addad

Algorithms often carry out equally many computations for "easy" and "hard" problem instances. In particular, algorithms for finding nearest neighbors typically have the same running time regardless of the particular problem instance. In…

Data Structures and Algorithms · Computer Science 2020-03-25 Daniel LeJeune , Richard G. Baraniuk , Reinhard Heckel

The $k$-median and $k$-means clustering objectives are classic objectives for modeling clustering in a metric space. Given a set of points in a metric space, the goal of the $k$-median (resp. $k$-means) problem is to find $k$ representative…

Computational Geometry · Computer Science 2026-03-11 Vincent Cohen-Addad , Karthik C. S. , David Saulpic , Chris Schwiegelshohn

Clustering is a basic task in data analysis and machine learning, and the optimization of clustering objectives are well-studied optimization problems; amongst these, the $k$-Means objective is arguably the most well known. Given a…

Data Structures and Algorithms · Computer Science 2026-05-29 Moses Charikar , Vincent Cohen-Addad , Ruiquan Gao , Fabrizio Grandoni , Euiwoong Lee , Ernest van Wijland

For very large values of $k$, we consider methods for fast $k$-means clustering of massive datasets with $10^7\sim10^9$ points in high-dimensions ($d\geq100$). All current practical methods for this problem have runtimes at least…

Machine Learning · Computer Science 2025-02-11 Jack Spalding-Jamieson , Eliot Wong Robson , Da Wei Zheng

In this paper, we investigate the learning-augmented $k$-median clustering problem, which aims to improve the performance of traditional clustering algorithms by preprocessing the point set with a predictor of error rate $\alpha \in [0,1)$.…

Data Structures and Algorithms · Computer Science 2026-03-12 Kangke Cheng , Shihong Song , Guanlin Mo , Hu Ding

We give a local search based algorithm for $k$-median and $k$-means (and more generally for any $k$-clustering with $\ell_p$ norm cost function) from the perspective of individual fairness. More precisely, for a point $x$ in a point set $P$…

Data Structures and Algorithms · Computer Science 2020-09-23 Sepideh Mahabadi , Ali Vakilian

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…

Data Structures and Algorithms · Computer Science 2025-03-26 Matthijs Ebbens , Nicole Funk , Jan Höckendorff , Christian Sohler , Vera Weil

The Uncapacitated Facility Location (UFL) problem is one of the most fundamental clustering problems: Given a set of clients $C$ and a set of facilities $F$ in a metric space $(C \cup F, dist)$ with facility costs $open : F \to…

Data Structures and Algorithms · Computer Science 2026-01-29 Vincent Cohen-Addad , Fabrizio Grandoni , Euiwoong Lee , Chris Schwiegelshohn

Following recent advances in combining approximation algorithms with fixed-parameter tractability (FPT), we study FPT-time approximation algorithms for minimum-norm $k$-clustering problems, parameterized by the number $k$ of open…

Data Structures and Algorithms · Computer Science 2026-05-07 Han Dai , Shi Li , Sijin Peng