Search Results for author: Lifeng Lai

Found 27 papers, 0 papers with code

Distributed Dual Coordinate Ascent with Imbalanced Data on a General Tree Network

no code implementations28 Aug 2023 Myung Cho, Lifeng Lai, Weiyu Xu

In this paper, we investigate the impact of imbalanced data on the convergence of distributed dual coordinate ascent in a tree network for solving an empirical loss minimization problem in distributed machine learning.

Minimax Optimal $Q$ Learning with Nearest Neighbors

no code implementations3 Aug 2023 Puning Zhao, Lifeng Lai

A modification of the original $Q$ learning method was proposed in (Shah and Xie, 2018), which estimates $Q$ values with nearest neighbors.

Q-Learning

Efficient Action Robust Reinforcement Learning with Probabilistic Policy Execution Uncertainty

no code implementations15 Jul 2023 Guanlin Liu, Zhihan Zhou, Han Liu, Lifeng Lai

Robust reinforcement learning (RL) aims to find a policy that optimizes the worst-case performance in the face of uncertainties.

reinforcement-learning Reinforcement Learning (RL)

Fairness-aware Regression Robust to Adversarial Attacks

no code implementations4 Nov 2022 Yulu Jin, Lifeng Lai

In this paper, we take a first step towards answering the question of how to design fair machine learning algorithms that are robust to adversarial attacks.

Fairness regression

Efficiently Escaping Saddle Points in Bilevel Optimization

no code implementations8 Feb 2022 Minhui Huang, Xuxing Chen, Kaiyi Ji, Shiqian Ma, Lifeng Lai

Moreover, we propose an inexact NEgative-curvature-Originated-from-Noise Algorithm (iNEON), a pure first-order algorithm that can escape saddle point and find local minimum of stochastic bilevel optimization.

Bilevel Optimization

Efficient Action Poisoning Attacks on Linear Contextual Bandits

no code implementations10 Dec 2021 Guanlin Liu, Lifeng Lai

We show that, in both white-box and black-box settings, the proposed attack schemes can force the LinUCB agent to pull a target arm very frequently by spending only logarithm cost.

Multi-Armed Bandits

Provably Efficient Black-Box Action Poisoning Attacks Against Reinforcement Learning

no code implementations NeurIPS 2021 Guanlin Liu, Lifeng Lai

In this paper, we introduce a new class of attacks named action poisoning attacks, where an adversary can change the action signal selected by the agent.

reinforcement-learning Reinforcement Learning (RL)

On the Convergence of Projected Alternating Maximization for Equitable and Optimal Transport

no code implementations29 Sep 2021 Minhui Huang, Shiqian Ma, Lifeng Lai

This paper studies the equitable and optimal transport (EOT) problem, which has many applications such as fair division problems and optimal transport with multiple agents etc.

Optimal Stochastic Nonconvex Optimization with Bandit Feedback

no code implementations30 Mar 2021 Puning Zhao, Lifeng Lai

In this paper, we analyze the continuous armed bandit problems for nonconvex cost functions under certain smoothness and sublevel set assumptions.

Projection Robust Wasserstein Barycenters

no code implementations5 Feb 2021 Minhui Huang, Shiqian Ma, Lifeng Lai

One of the popular solution methods for this task is to compute the barycenter of the probability measures under the Wasserstein metric.

Clustering Riemannian optimization

A Riemannian Block Coordinate Descent Method for Computing the Projection Robust Wasserstein Distance

no code implementations9 Dec 2020 Minhui Huang, Shiqian Ma, Lifeng Lai

We show that the complexity of arithmetic operations for RBCD to obtain an $\epsilon$-stationary point is $O(\epsilon^{-3})$.

On the Adversarial Robustness of LASSO Based Feature Selection

no code implementations20 Oct 2020 Fuwei Li, Lifeng Lai, Shuguang Cui

We formulate the modification strategy of the adversary as a bi-level optimization problem.

Adversarial Robustness feature selection

Analysis of KNN Density Estimation

no code implementations30 Sep 2020 Puning Zhao, Lifeng Lai

We show that kNN density estimation is minimax optimal under both $\ell_1$ and $\ell_\infty$ criteria, if the support set is known.

Density Estimation

Robust Low-rank Matrix Completion via an Alternating Manifold Proximal Gradient Continuation Method

no code implementations18 Aug 2020 Minhui Huang, Shiqian Ma, Lifeng Lai

This problem aims to decompose a partially observed matrix into the superposition of a low-rank matrix and a sparse matrix, where the sparse matrix captures the grossly corrupted entries of the matrix.

Low-Rank Matrix Completion Riemannian optimization

Optimal Feature Manipulation Attacks Against Linear Regression

no code implementations29 Feb 2020 Fuwei Li, Lifeng Lai, Shuguang Cui

In this paper, we investigate how to manipulate the coefficients obtained via linear regression by adding carefully designed poisoning data points to the dataset or modify the original data points.

regression

Minimax Optimal Estimation of KL Divergence for Continuous Distributions

no code implementations26 Feb 2020 Puning Zhao, Lifeng Lai

Estimating Kullback-Leibler divergence from identical and independently distributed samples is an important problem in various domains.

Action-Manipulation Attacks Against Stochastic Bandits: Attacks and Defense

no code implementations19 Feb 2020 Guanlin Liu, Lifeng Lai

To defend against this class of attacks, we introduce a novel algorithm that is robust to action-manipulation attacks when an upper bound for the total attack cost is given.

Minimax Rate Optimal Adaptive Nearest Neighbor Classification and Regression

no code implementations22 Oct 2019 Puning Zhao, Lifeng Lai

For both classification and regression problems, existing works have shown that, if the distribution of the feature vector has bounded support and the probability density function is bounded away from zero in its support, the convergence rate of the standard kNN method, in which k is the same for all test samples, is minimax optimal.

Classification General Classification +1

On the Adversarial Robustness of Subspace Learning

no code implementations17 Aug 2019 Fuwei Li, Lifeng Lai, Shuguang Cui

We first characterize the optimal rank-one attack strategy that maximizes the subspace distance between the subspace learned from the original data matrix and that learned from the modified data matrix.

Adversarial Robustness

On the Adversarial Robustness of Multivariate Robust Estimation

no code implementations27 Mar 2019 Erhan Bayraktar, Lifeng Lai

In this paper, we investigate the adversarial robustness of multivariate $M$-Estimators.

Adversarial Robustness

Quick Best Action Identification in Linear Bandit Problems

no code implementations2 Dec 2018 Jun Geng, Lifeng Lai

In the considered best action identification problem, instead of minimizing the accumulative regret as done in existing works, the learner aims to obtain an accurate estimate of the underlying parameter based on his action and reward sequences.

Analysis of KNN Information Estimators for Smooth Distributions

no code implementations27 Oct 2018 Puning Zhao, Lifeng Lai

Existing work has analyzed the convergence rate of this estimator for random variables whose densities are bounded away from zero in its support.

Distributed Dual Coordinate Ascent in General Tree Networks and Communication Network Effect on Synchronous Machine Learning

no code implementations14 Mar 2017 Myung Cho, Lifeng Lai, Weiyu Xu

Additionally, we show that adapting number of local and global iterations to network communication delays in the distributed dual coordinated ascent algorithm can improve its convergence speed.

BIG-bench Machine Learning

On Randomized Distributed Coordinate Descent with Quantized Updates

no code implementations18 Sep 2016 Mostafa El Gamal, Lifeng Lai

In this paper, we study the randomized distributed coordinate descent algorithm with quantized updates.

Quantization regression

Precise Phase Transition of Total Variation Minimization

no code implementations15 Sep 2015 Bingwen Zhang, Weiyu Xu, Jian-Feng Cai, Lifeng Lai

Characterizing the phase transitions of convex optimizations in recovering structured signals or data is of central importance in compressed sensing, machine learning and statistics.

Denoising

Are Slepian-Wolf Rates Necessary for Distributed Parameter Estimation?

no code implementations11 Aug 2015 Mostafa El Gamal, Lifeng Lai

We consider a distributed parameter estimation problem, in which multiple terminals send messages related to their local observations using limited rates to a fusion center who will obtain an estimate of a parameter related to observations of all terminals.

Cannot find the paper you are looking for? You can Submit a new open access paper.