Recycling History: Efficient Recommendations from Contextual Dueling Bandits

Fuente: arXiv
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Main Authors: Sankagiri, Suryanarayana, Etesami, Jalal, Fatemi, Pouria, Grossglauser, Matthias
Format: Preprint
Published: 2025
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author Sankagiri, Suryanarayana
Etesami, Jalal
Fatemi, Pouria
Grossglauser, Matthias
author_facet Sankagiri, Suryanarayana
Etesami, Jalal
Fatemi, Pouria
Grossglauser, Matthias
contents The contextual duelling bandit problem models adaptive recommender systems, where the algorithm presents a set of items to the user, and the user's choice reveals their preference. This setup is well suited for implicit choices users make when navigating a content platform, but does not capture other possible comparison queries. Motivated by the fact that users provide more reliable feedback after consuming items, we propose a new bandit model that can be described as follows. The algorithm recommends one item per time step; after consuming that item, the user is asked to compare it with another item chosen from the user's consumption history. Importantly, in our model, this comparison item can be chosen without incurring any additional regret, potentially leading to better performance. However, the regret analysis is challenging because of the temporal dependency in the user's history. To overcome this challenge, we first show that the algorithm can construct informative queries provided the history is rich, i.e., satisfies a certain diversity condition. We then show that a short initial random exploration phase is sufficient for the algorithm to accumulate a rich history with high probability. This result, proven via matrix concentration bounds, yields $O(\sqrt{T})$ regret guarantees. Additionally, our simulations show that reusing past items for comparisons can lead to significantly lower regret than only comparing between simultaneously recommended items.
format Preprint
id arxiv_https___arxiv_org_abs_2508_18841
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Recycling History: Efficient Recommendations from Contextual Dueling Bandits
Sankagiri, Suryanarayana
Etesami, Jalal
Fatemi, Pouria
Grossglauser, Matthias
Machine Learning
The contextual duelling bandit problem models adaptive recommender systems, where the algorithm presents a set of items to the user, and the user's choice reveals their preference. This setup is well suited for implicit choices users make when navigating a content platform, but does not capture other possible comparison queries. Motivated by the fact that users provide more reliable feedback after consuming items, we propose a new bandit model that can be described as follows. The algorithm recommends one item per time step; after consuming that item, the user is asked to compare it with another item chosen from the user's consumption history. Importantly, in our model, this comparison item can be chosen without incurring any additional regret, potentially leading to better performance. However, the regret analysis is challenging because of the temporal dependency in the user's history. To overcome this challenge, we first show that the algorithm can construct informative queries provided the history is rich, i.e., satisfies a certain diversity condition. We then show that a short initial random exploration phase is sufficient for the algorithm to accumulate a rich history with high probability. This result, proven via matrix concentration bounds, yields $O(\sqrt{T})$ regret guarantees. Additionally, our simulations show that reusing past items for comparisons can lead to significantly lower regret than only comparing between simultaneously recommended items.
title Recycling History: Efficient Recommendations from Contextual Dueling Bandits
topic Machine Learning
url https://arxiv.org/abs/2508.18841