ExDBSCAN: Explaining DBSCAN with Counterfactual Reasoning -- Additional Material

Fuente: arXiv
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Main Authors: Matthews, Pernille, Krieger, Lena, Amico, Tommaso, Zimek, Artur, Seidl, Thomas, Assent, Ira
Format: Preprint
Published: 2026
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author Matthews, Pernille
Krieger, Lena
Amico, Tommaso
Zimek, Artur
Seidl, Thomas
Assent, Ira
author_facet Matthews, Pernille
Krieger, Lena
Amico, Tommaso
Zimek, Artur
Seidl, Thomas
Assent, Ira
contents Clustering is an unsupervised technique for grouping data points by similarity. While explainability methods exist for supervised machine learning, they are not directly applicable to clustering, making it challenging to understand cluster assignments. This interpretability gap is particularly evident in the popular density-based method DBSCAN, which assigns points as inliers (cluster members in dense regions) or outliers (noise points in sparse regions). DBSCAN does not provide insight into why a particular point receives its assignment or whether its assignment is robust to small changes in the data. To address the lack of explainability, we introduce ExDBSCAN, a density-aware, post-hoc explanation method. ExDBSCAN offers actionable counterfactual explanations, with theoretical guarantees for validity. It generates multiple counterfactuals using a density connected weighted graph, adopting a physics-inspired model that repels counterfactual candidates from one another (diversity), while pulling them toward the instance to explain (proximity). Empirical evaluation on 30 tabular datasets comparing against four baselines shows that ExDBSCAN outperforms all baselines while attaining perfect validity and retrieving diverse, proximal counterfactuals.
format Preprint
id arxiv_https___arxiv_org_abs_2605_30225
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle ExDBSCAN: Explaining DBSCAN with Counterfactual Reasoning -- Additional Material
Matthews, Pernille
Krieger, Lena
Amico, Tommaso
Zimek, Artur
Seidl, Thomas
Assent, Ira
Machine Learning
Clustering is an unsupervised technique for grouping data points by similarity. While explainability methods exist for supervised machine learning, they are not directly applicable to clustering, making it challenging to understand cluster assignments. This interpretability gap is particularly evident in the popular density-based method DBSCAN, which assigns points as inliers (cluster members in dense regions) or outliers (noise points in sparse regions). DBSCAN does not provide insight into why a particular point receives its assignment or whether its assignment is robust to small changes in the data. To address the lack of explainability, we introduce ExDBSCAN, a density-aware, post-hoc explanation method. ExDBSCAN offers actionable counterfactual explanations, with theoretical guarantees for validity. It generates multiple counterfactuals using a density connected weighted graph, adopting a physics-inspired model that repels counterfactual candidates from one another (diversity), while pulling them toward the instance to explain (proximity). Empirical evaluation on 30 tabular datasets comparing against four baselines shows that ExDBSCAN outperforms all baselines while attaining perfect validity and retrieving diverse, proximal counterfactuals.
title ExDBSCAN: Explaining DBSCAN with Counterfactual Reasoning -- Additional Material
topic Machine Learning
url https://arxiv.org/abs/2605.30225