Search Results for author: Nian Si

Found 16 papers, 5 papers with code

Distributionally Robust Policy Evaluation and Learning in Offline Contextual Bandits

no code implementations ICML 2020 Nian Si, Fan Zhang, Zhengyuan Zhou, Jose Blanchet

We first present a policy evaluation procedure in the ambiguous environment and also give a heuristic algorithm to solve the distributionally robust policy learning problems efficiently.

Multi-Armed Bandits

Seller-Side Experiments under Interference Induced by Feedback Loops in Two-Sided Platforms

no code implementations29 Jan 2024 Zhihua Zhu, Zheng Cai, Liang Zheng, Nian Si

Two-sided platforms are central to modern commerce and content sharing and often utilize A/B testing for developing new features.

counterfactual

Singular Control of (Reflected) Brownian Motion: A Computational Method Suitable for Queueing Applications

1 code implementation19 Dec 2023 Baris Ata, J. Michael Harrison, Nian Si

Motivated by applications in queueing theory, we consider a class of singular stochastic control problems whose state space is the d-dimensional positive orthant.

On the Foundation of Distributionally Robust Reinforcement Learning

no code implementations15 Nov 2023 Shengbo Wang, Nian Si, Jose Blanchet, Zhengyuan Zhou

This is accomplished through a comprehensive modeling framework centered around distributionally robust Markov decision processes (DRMDPs).

reinforcement-learning

Tackling Interference Induced by Data Training Loops in A/B Tests: A Weighted Training Approach

no code implementations26 Oct 2023 Nian Si

In modern recommendation systems, the standard pipeline involves training machine learning models on historical data to predict user behaviors and improve recommendations continuously.

Recommendation Systems

Drift Control of High-Dimensional RBM: A Computational Method Based on Neural Networks

1 code implementation20 Sep 2023 Baris Ata, J. Michael Harrison, Nian Si

Motivated by applications in queueing theory, we consider a stochastic control problem whose state space is the $d$-dimensional positive orthant.

Sample Complexity of Variance-reduced Distributionally Robust Q-learning

no code implementations28 May 2023 Shengbo Wang, Nian Si, Jose Blanchet, Zhengyuan Zhou

Further, the variance-reduced distributionally robust Q-learning combines the synchronous Q-learning with variance-reduction techniques to enhance its performance.

Decision Making Q-Learning

A Finite Sample Complexity Bound for Distributionally Robust Q-learning

no code implementations26 Feb 2023 Shengbo Wang, Nian Si, Jose Blanchet, Zhengyuan Zhou

We consider a reinforcement learning setting in which the deployment environment is different from the training environment.

Q-Learning

Calibration Matters: Tackling Maximization Bias in Large-scale Advertising Recommendation Systems

1 code implementation19 May 2022 Yewen Fan, Nian Si, Kun Zhang

Calibration is defined as the ratio of the average predicted click rate to the true click rate.

Recommendation Systems

Selecting the Best Optimizing System

1 code implementation9 Jan 2022 Nian Si, Zeyu Zheng

An SBOS problem compares different systems based on their expected performances under their own optimally chosen decision to select the best, without advance knowledge of expected performances of the systems nor the optimizing decision inside each system.

Testing Group Fairness via Optimal Transport Projections

no code implementations2 Jun 2021 Nian Si, Karthyek Murthy, Jose Blanchet, Viet Anh Nguyen

We present a statistical testing framework to detect if a given machine learning classifier fails to satisfy a wide range of group fairness notions.

Fairness

Quantifying the Empirical Wasserstein Distance to a Set of Measures: Beating the Curse of Dimensionality

no code implementations NeurIPS 2020 Nian Si, Jose Blanchet, Soumyadip Ghosh, Mark Squillante

We consider the problem of estimating the Wasserstein distance between the empirical measure and a set of probability measures whose expectations over a class of functions (hypothesis class) are constrained.

Robust Bayesian Classification Using an Optimistic Score Ratio

1 code implementation ICML 2020 Viet Anh Nguyen, Nian Si, Jose Blanchet

The optimistic score searches for the distribution that is most plausible to explain the observed outcomes in the testing sample among all distributions belonging to the contextual ambiguity set which is prescribed using a limited structural constraint on the mean vector and the covariance matrix of the underlying contextual distribution.

Binary Classification Classification +1

Distributionally Robust Batch Contextual Bandits

no code implementations10 Jun 2020 Nian Si, Fan Zhang, Zhengyuan Zhou, Jose Blanchet

Leveraging this evaluation scheme, we further propose a novel learning algorithm that is able to learn a policy that is robust to adversarial perturbations and unknown covariate shifts with a performance guarantee based on the theory of uniform convergence.

Multi-Armed Bandits

Confidence Regions in Wasserstein Distributionally Robust Estimation

no code implementations4 Jun 2019 Jose Blanchet, Karthyek Murthy, Nian Si

Wasserstein distributionally robust optimization estimators are obtained as solutions of min-max problems in which the statistician selects a parameter minimizing the worst-case loss among all probability models within a certain distance (in a Wasserstein sense) from the underlying empirical measure.

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