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Main Authors: Jia, Chaoqi, Guo, Longkun, Liao, Kewen, Lu, Zhigang, Chen, Chao, Xue, Jason
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2601.11883
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author Jia, Chaoqi
Guo, Longkun
Liao, Kewen
Lu, Zhigang
Chen, Chao
Xue, Jason
author_facet Jia, Chaoqi
Guo, Longkun
Liao, Kewen
Lu, Zhigang
Chen, Chao
Xue, Jason
contents Clustering is a long-standing research problem and a fundamental tool in AI and data analysis. The traditional k-center problem, a fundamental theoretical challenge in clustering, has a best possible approximation ratio of 2, and any improvement to a ratio of 2 - ε would imply P = NP. In this work, we study the constrained k-center clustering problem, where instance-level cannot-link (CL) and must-link (ML) constraints are incorporated as background knowledge. Although general CL constraints significantly increase the hardness of approximation, previous work has shown that disjoint CL sets permit constant-factor approximations. However, whether local search can achieve such a guarantee in this setting remains an open question. To this end, we propose a novel local search framework based on a transformation to a dominating matching set problem, achieving the best possible approximation ratio of 2. The experimental results on both real-world and synthetic datasets demonstrate that our algorithm outperforms baselines in solution quality.
format Preprint
id arxiv_https___arxiv_org_abs_2601_11883
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Approximation Algorithm for Constrained $k$-Center Clustering: A Local Search Approach
Jia, Chaoqi
Guo, Longkun
Liao, Kewen
Lu, Zhigang
Chen, Chao
Xue, Jason
Machine Learning
Clustering is a long-standing research problem and a fundamental tool in AI and data analysis. The traditional k-center problem, a fundamental theoretical challenge in clustering, has a best possible approximation ratio of 2, and any improvement to a ratio of 2 - ε would imply P = NP. In this work, we study the constrained k-center clustering problem, where instance-level cannot-link (CL) and must-link (ML) constraints are incorporated as background knowledge. Although general CL constraints significantly increase the hardness of approximation, previous work has shown that disjoint CL sets permit constant-factor approximations. However, whether local search can achieve such a guarantee in this setting remains an open question. To this end, we propose a novel local search framework based on a transformation to a dominating matching set problem, achieving the best possible approximation ratio of 2. The experimental results on both real-world and synthetic datasets demonstrate that our algorithm outperforms baselines in solution quality.
title Approximation Algorithm for Constrained $k$-Center Clustering: A Local Search Approach
topic Machine Learning
url https://arxiv.org/abs/2601.11883