Conservative Contextual Combinatorial Cascading Bandit

Contextual combinatorial cascading bandit (<inline-formula> <tex-math notation="LaTeX">$C^{3}$ </tex-math></inline-formula>-bandit) is a powerful multi-armed bandit framework that balances the tradeoff between exploration and exploitation in the learning process. It...

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Autor principal: Kun Wang
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Publicado: IEEE 2021
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spelling oai:doaj.org-article:b2cfe5670c4048999cc7a7df5c529f402021-11-17T00:00:37ZConservative Contextual Combinatorial Cascading Bandit2169-353610.1109/ACCESS.2021.3124416https://doaj.org/article/b2cfe5670c4048999cc7a7df5c529f402021-01-01T00:00:00Zhttps://ieeexplore.ieee.org/document/9594856/https://doaj.org/toc/2169-3536Contextual combinatorial cascading bandit (<inline-formula> <tex-math notation="LaTeX">$C^{3}$ </tex-math></inline-formula>-bandit) is a powerful multi-armed bandit framework that balances the tradeoff between exploration and exploitation in the learning process. It well captures users&#x2019; click behavior and has been applied in a broad spectrum of real-world applications such as recommender systems and search engines. However, such a framework does not provide a performance guarantee of the initial exploration phase. To that end, we propose <italic>conservative contextual combinatorial cascading bandit (<inline-formula> <tex-math notation="LaTeX">$C^{4}$ </tex-math></inline-formula>-bandit)</italic> model, aiming to address the aforementioned crucial modeling issues. In this problem, the learning agent is given some contexts and recommends a list of items not worse than the baseline strategy, and then observes the reward by some stopping rule. The objective is now to maximize the reward while simultaneously satisfying the safety constraint, i.e. guaranteeing the algorithm to perform at least as well as a baseline strategy. To tackle this new problem, we extend an online learning algorithm, called Upper Confidence Bound (UCB), to deal with a critical tradeoff between exploitation and exploration and employ the conservative mechanism to properly handle the safety constraints. By carefully integrating these two techniques, we develop a new algorithm, called <inline-formula> <tex-math notation="LaTeX">$C^{4}$ </tex-math></inline-formula>-UCB for this problem. Further, we rigorously prove the n-step upper bound in two situations: known baseline reward and unknown baseline reward. The regret in both situations is only enlarged by an additive constant term compared to results of <inline-formula> <tex-math notation="LaTeX">$C^{3}$ </tex-math></inline-formula>-bandit. Finally, experiments on synthetic and realistic datasets demonstrate its advantages.Kun WangIEEEarticleMachine learningmulti-armed banditonline learningrecommender systemElectrical engineering. Electronics. Nuclear engineeringTK1-9971ENIEEE Access, Vol 9, Pp 151434-151443 (2021)
institution DOAJ
collection DOAJ
language EN
topic Machine learning
multi-armed bandit
online learning
recommender system
Electrical engineering. Electronics. Nuclear engineering
TK1-9971
spellingShingle Machine learning
multi-armed bandit
online learning
recommender system
Electrical engineering. Electronics. Nuclear engineering
TK1-9971
Kun Wang
Conservative Contextual Combinatorial Cascading Bandit
description Contextual combinatorial cascading bandit (<inline-formula> <tex-math notation="LaTeX">$C^{3}$ </tex-math></inline-formula>-bandit) is a powerful multi-armed bandit framework that balances the tradeoff between exploration and exploitation in the learning process. It well captures users&#x2019; click behavior and has been applied in a broad spectrum of real-world applications such as recommender systems and search engines. However, such a framework does not provide a performance guarantee of the initial exploration phase. To that end, we propose <italic>conservative contextual combinatorial cascading bandit (<inline-formula> <tex-math notation="LaTeX">$C^{4}$ </tex-math></inline-formula>-bandit)</italic> model, aiming to address the aforementioned crucial modeling issues. In this problem, the learning agent is given some contexts and recommends a list of items not worse than the baseline strategy, and then observes the reward by some stopping rule. The objective is now to maximize the reward while simultaneously satisfying the safety constraint, i.e. guaranteeing the algorithm to perform at least as well as a baseline strategy. To tackle this new problem, we extend an online learning algorithm, called Upper Confidence Bound (UCB), to deal with a critical tradeoff between exploitation and exploration and employ the conservative mechanism to properly handle the safety constraints. By carefully integrating these two techniques, we develop a new algorithm, called <inline-formula> <tex-math notation="LaTeX">$C^{4}$ </tex-math></inline-formula>-UCB for this problem. Further, we rigorously prove the n-step upper bound in two situations: known baseline reward and unknown baseline reward. The regret in both situations is only enlarged by an additive constant term compared to results of <inline-formula> <tex-math notation="LaTeX">$C^{3}$ </tex-math></inline-formula>-bandit. Finally, experiments on synthetic and realistic datasets demonstrate its advantages.
format article
author Kun Wang
author_facet Kun Wang
author_sort Kun Wang
title Conservative Contextual Combinatorial Cascading Bandit
title_short Conservative Contextual Combinatorial Cascading Bandit
title_full Conservative Contextual Combinatorial Cascading Bandit
title_fullStr Conservative Contextual Combinatorial Cascading Bandit
title_full_unstemmed Conservative Contextual Combinatorial Cascading Bandit
title_sort conservative contextual combinatorial cascading bandit
publisher IEEE
publishDate 2021
url https://doaj.org/article/b2cfe5670c4048999cc7a7df5c529f40
work_keys_str_mv AT kunwang conservativecontextualcombinatorialcascadingbandit
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