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Hauptverfasser: Stratigi, Maria, Bikakis, Nikos, Stefanidis, Kostas
Format: Preprint
Veröffentlicht: 2026
Schlagworte:
Online-Zugang:https://arxiv.org/abs/2601.16882
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author Stratigi, Maria
Bikakis, Nikos
Stefanidis, Kostas
author_facet Stratigi, Maria
Bikakis, Nikos
Stefanidis, Kostas
contents Group recommender systems help users make collective choices but often lack transparency, leaving group members uncertain about why items are suggested. Existing explanation methods focus on individuals, offering limited support for groups where multiple preferences interact. In this paper, we propose a framework for group counterfactual explanations, which reveal how removing specific past interactions would change a group recommendation. We formalize this concept, introduce utility and fairness measures tailored to groups, and design heuristic algorithms, such as Pareto-based filtering and grow-and-prune strategies, for efficient explanation discovery. Experiments on MovieLens and Amazon datasets show clear trade-offs: low-cost methods produce larger, less fair explanations, while other approaches yield concise and balanced results at higher cost. Furthermore, the Pareto-filtering heuristic demonstrates significant efficiency improvements in sparse settings.
format Preprint
id arxiv_https___arxiv_org_abs_2601_16882
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Explaining Group Recommendations via Counterfactuals
Stratigi, Maria
Bikakis, Nikos
Stefanidis, Kostas
Information Retrieval
Artificial Intelligence
H.3; H.4; I.2
Group recommender systems help users make collective choices but often lack transparency, leaving group members uncertain about why items are suggested. Existing explanation methods focus on individuals, offering limited support for groups where multiple preferences interact. In this paper, we propose a framework for group counterfactual explanations, which reveal how removing specific past interactions would change a group recommendation. We formalize this concept, introduce utility and fairness measures tailored to groups, and design heuristic algorithms, such as Pareto-based filtering and grow-and-prune strategies, for efficient explanation discovery. Experiments on MovieLens and Amazon datasets show clear trade-offs: low-cost methods produce larger, less fair explanations, while other approaches yield concise and balanced results at higher cost. Furthermore, the Pareto-filtering heuristic demonstrates significant efficiency improvements in sparse settings.
title Explaining Group Recommendations via Counterfactuals
topic Information Retrieval
Artificial Intelligence
H.3; H.4; I.2
url https://arxiv.org/abs/2601.16882