일시: 2024년 3월 21일(목), 14:00~16:00
장소: 판교 테크노밸리 산업수학혁신센터 세미나실
발표자: 오민환 교수(서울대학교)
주요내용: Cascading Contextual Assortment Bandits
Multi-armed bandit is a fundamental sequential decision-making problem that is often used to model interactions between users and a recommender agent. We propose a new combinatorial bandit model, the cascading contextual contextual assortment bandit. This model serves as a generalization of both existing cascading bandits and assortment bandits, broadening their applicability in practice. For this model, we propose our first UCB bandit algorithm, UCB-CCA. We prove that this algorithm achieves a T-step regret upper-bound of O((d/κ)√T) sharper than existing bounds for cascading contextual bandits by eliminating dependence on cascade length K. To improve the dependence on problem-dependent constant κ, we introduce our second algorithm, UCB-CCA+, which leverages a new Bernstein-type concentration result. This algorithm achieves O(d√T) without dependence on κ in the leading term. We substantiate our theoretical claims with numerical experiments, demonstrating the practical efficacy of our proposed methods.
일시: 2024년 3월 21일(목), 14:00~16:00
장소: 판교 테크노밸리 산업수학혁신센터 세미나실
발표자: 오민환 교수(서울대학교)
주요내용: Cascading Contextual Assortment Bandits
Multi-armed bandit is a fundamental sequential decision-making problem that is often used to model interactions between users and a recommender agent. We propose a new combinatorial bandit model, the cascading contextual contextual assortment bandit. This model serves as a generalization of both existing cascading bandits and assortment bandits, broadening their applicability in practice. For this model, we propose our first UCB bandit algorithm, UCB-CCA. We prove that this algorithm achieves a T-step regret upper-bound of O((d/κ)√T) sharper than existing bounds for cascading contextual bandits by eliminating dependence on cascade length K. To improve the dependence on problem-dependent constant κ, we introduce our second algorithm, UCB-CCA+, which leverages a new Bernstein-type concentration result. This algorithm achieves O(d√T) without dependence on κ in the leading term. We substantiate our theoretical claims with numerical experiments, demonstrating the practical efficacy of our proposed methods.