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arXiv · 2605.17285

UNR-Explainer: Counterfactual Explanations for Unsupervised Node Representation Learning Models

Hyunju Kang·Geonhee Han·Hogun Park
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Abstract

Node representation learning, such as Graph Neural Networks (GNNs), has emerged as a pivotal method in machine learning. The demand for reliable explanation generation surges, yet unsupervised models remain underexplored. To bridge this gap, we introduce a method for generating counterfactual (CF) explanations in unsupervised node representation learning. We identify the most important subgraphs that cause a significant change in the k-nearest neighbors of a node of interest in the learned embedding space upon perturbation. The k-nearest neighbor-based CF explanation method provides simple, yet pivotal, information for understanding unsupervised downstream tasks, such as top-k link prediction and clustering. Consequently, we introduce UNR-Explainer for generating expressive CF explanations for Unsupervised Node Representation learning methods based on a Monte Carlo Tree Search (MCTS). The proposed method demonstrates superior performance on diverse datasets for unsupervised GraphSAGE and DGI.

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Hyunju Kang, Geonhee Han, Hogun Park. 2026-05-17. UNR-Explainer: Counterfactual Explanations for Unsupervised Node Representation Learning Models. https://arxiv.org/abs/2605.17285

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