A Faster Algorithm for Constrained Correlation Clustering

Fuente: arXiv
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Autores principales: Fischer, Nick, Kipouridis, Evangelos, Klausen, Jonas, Thorup, Mikkel
Formato: Preprint
Publicado: 2025
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author Fischer, Nick
Kipouridis, Evangelos
Klausen, Jonas
Thorup, Mikkel
author_facet Fischer, Nick
Kipouridis, Evangelos
Klausen, Jonas
Thorup, Mikkel
contents In the Correlation Clustering problem we are given $n$ nodes, and a preference for each pair of nodes indicating whether we prefer the two endpoints to be in the same cluster or not. The output is a clustering inducing the minimum number of violated preferences. In certain cases, however, the preference between some pairs may be too important to be violated. The constrained version of this problem specifies pairs of nodes that must be in the same cluster as well as pairs that must not be in the same cluster (hard constraints). The output clustering has to satisfy all hard constraints while minimizing the number of violated preferences. Constrained Correlation Clustering is APX-Hard and has been approximated within a factor 3 by van Zuylen et al. [SODA '07] using $Ω(n^{3ω})$ time. In this work, using a more combinatorial approach, we show how to approximate this problem significantly faster at the cost of a slightly weaker approximation factor. In particular, our algorithm runs in $\widetilde{O}(n^3)$ time and approximates Constrained Correlation Clustering within a factor 16. To achieve our result we need properties guaranteed by a particular influential algorithm for (unconstrained) Correlation Clustering, the CC-PIVOT algorithm. This algorithm chooses a pivot node $u$, creates a cluster containing $u$ and all its preferred nodes, and recursively solves the rest of the problem. As a byproduct of our work, we provide a derandomization of the CC-PIVOT algorithm that still achieves the 3-approximation; furthermore, we show that there exist instances where no ordering of the pivots can give a $(3-\varepsilon)$-approximation, for any constant $\varepsilon$. Finally, we introduce a node-weighted version of Correlation Clustering, which can be approximated within factor 3 using our insights on Constrained Correlation Clustering.
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id arxiv_https___arxiv_org_abs_2501_03154
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Faster Algorithm for Constrained Correlation Clustering
Fischer, Nick
Kipouridis, Evangelos
Klausen, Jonas
Thorup, Mikkel
Data Structures and Algorithms
In the Correlation Clustering problem we are given $n$ nodes, and a preference for each pair of nodes indicating whether we prefer the two endpoints to be in the same cluster or not. The output is a clustering inducing the minimum number of violated preferences. In certain cases, however, the preference between some pairs may be too important to be violated. The constrained version of this problem specifies pairs of nodes that must be in the same cluster as well as pairs that must not be in the same cluster (hard constraints). The output clustering has to satisfy all hard constraints while minimizing the number of violated preferences. Constrained Correlation Clustering is APX-Hard and has been approximated within a factor 3 by van Zuylen et al. [SODA '07] using $Ω(n^{3ω})$ time. In this work, using a more combinatorial approach, we show how to approximate this problem significantly faster at the cost of a slightly weaker approximation factor. In particular, our algorithm runs in $\widetilde{O}(n^3)$ time and approximates Constrained Correlation Clustering within a factor 16. To achieve our result we need properties guaranteed by a particular influential algorithm for (unconstrained) Correlation Clustering, the CC-PIVOT algorithm. This algorithm chooses a pivot node $u$, creates a cluster containing $u$ and all its preferred nodes, and recursively solves the rest of the problem. As a byproduct of our work, we provide a derandomization of the CC-PIVOT algorithm that still achieves the 3-approximation; furthermore, we show that there exist instances where no ordering of the pivots can give a $(3-\varepsilon)$-approximation, for any constant $\varepsilon$. Finally, we introduce a node-weighted version of Correlation Clustering, which can be approximated within factor 3 using our insights on Constrained Correlation Clustering.
title A Faster Algorithm for Constrained Correlation Clustering
topic Data Structures and Algorithms
url https://arxiv.org/abs/2501.03154