Search Results for author: Hoi-To Wai

Found 49 papers, 5 papers with code

Network Games Induced Prior for Graph Topology Learning

no code implementations31 Oct 2024 Chenyue Zhang, Shangyuan Liu, Hoi-To Wai, Anthony Man-Cho So

We draw theoretical insights on the optimal graph structure of the bilevel program and show that they agree with the topology in several man-made networks.

Graph Learning

Fully Stochastic Primal-dual Gradient Algorithm for Non-convex Optimization on Random Graphs

1 code implementation24 Oct 2024 Chung-Yiu Yau, Haoming Liu, Hoi-To Wai

Stochastic decentralized optimization algorithms often suffer from issues such as synchronization overhead and intermittent communication.

Blocking

Getting More Juice Out of the SFT Data: Reward Learning from Human Demonstration Improves SFT for LLM Alignment

1 code implementation28 May 2024 Jiaxiang Li, Siliang Zeng, Hoi-To Wai, Chenliang Li, Alfredo Garcia, Mingyi Hong

State-of-the-art techniques such as Reinforcement Learning from Human Feedback (RLHF) often consist of two stages: 1) supervised fine-tuning (SFT), where the model is fine-tuned by learning from human demonstration data; 2) Preference learning, where preference data is used to learn a reward model, which is in turn used by a reinforcement learning (RL) step to fine-tune the model.

reinforcement-learning Reinforcement Learning +1

Dual-Delayed Asynchronous SGD for Arbitrarily Heterogeneous Data

no code implementations27 May 2024 Xiaolu Wang, Yuchang Sun, Hoi-To Wai, Jun Zhang

We consider the distributed learning problem with data dispersed across multiple workers under the orchestration of a central server.

On Detecting Low-pass Graph Signals under Partial Observations

no code implementations16 May 2024 Hoang-Son Nguyen, Hoi-To Wai

We propose a detector that certifies whether the partially observed graph signals are low pass filtered, without requiring the graph topology knowledge.

Clipped SGD Algorithms for Privacy Preserving Performative Prediction: Bias Amplification and Remedies

no code implementations17 Apr 2024 Qiang Li, Michal Yemini, Hoi-To Wai

This paper studies the convergence properties of these algorithms in a performative prediction setting, where the data distribution may shift due to the deployed prediction model.

Privacy Preserving

EMC$^2$: Efficient MCMC Negative Sampling for Contrastive Learning with Global Convergence

1 code implementation16 Apr 2024 Chung-Yiu Yau, Hoi-To Wai, Parameswaran Raman, Soumajyoti Sarkar, Mingyi Hong

We follow the global contrastive learning loss as introduced in SogCLR, and propose EMC$^2$ which utilizes an adaptive Metropolis-Hastings subroutine to generate hardness-aware negative samples in an online fashion during the optimization.

Contrastive Learning

Linear Speedup of Incremental Aggregated Gradient Methods on Streaming Data

no code implementations10 Sep 2023 Xiaolu Wang, Cheng Jin, Hoi-To Wai, Yuantao Gu

This paper considers a type of incremental aggregated gradient (IAG) method for large-scale distributed optimization.

Distributed Optimization

Blind Graph Matching Using Graph Signals

no code implementations27 Jun 2023 Hang Liu, Anna Scaglione, Hoi-To Wai

Our analysis shows that the blind matching outcome converges to the result obtained with known graph topologies when the signal sampling size is large and the signal noise is small.

Graph Matching

Clustering of Time-Varying Graphs Based on Temporal Label Smoothness

no code implementations11 May 2023 Katsuki Fukumoto, Koki Yamada, Yuichi Tanaka, Hoi-To Wai

In this paper, we formulate a node clustering of time-varying graphs as an optimization problem based on spectral clustering, with a smoothness constraint of the node labels.

Clustering Functional Connectivity +2

Stochastic Approximation Beyond Gradient for Signal Processing and Machine Learning

no code implementations22 Feb 2023 Aymeric Dieuleveut, Gersende Fort, Eric Moulines, Hoi-To Wai

Stochastic Approximation (SA) is a classical algorithm that has had since the early days a huge impact on signal processing, and nowadays on machine learning, due to the necessity to deal with a large amount of data observed with uncertainties.

Online Inference for Mixture Model of Streaming Graph Signals with Non-White Excitation

no code implementations28 Jul 2022 Yiran He, Hoi-To Wai

We study a mixture model of filtered low pass graph signals with possibly non-white and low-rank excitation.

Graph Learning

DoCoM: Compressed Decentralized Optimization with Near-Optimal Sample Complexity

1 code implementation1 Feb 2022 Chung-Yiu Yau, Hoi-To Wai

This paper proposes the Doubly Compressed Momentum-assisted stochastic gradient tracking algorithm $\texttt{DoCoM}$ for communication-efficient decentralized optimization.

On the Stability of Low Pass Graph Filter With a Large Number of Edge Rewires

no code implementations14 Oct 2021 Hoang-Son Nguyen, Yiran He, Hoi-To Wai

The stability of a graph filter characterizes the effect of topology perturbation on the output of a graph filter, a fundamental building block for GCNs.

Stochastic Block Model

An Empirical Study on Compressed Decentralized Stochastic Gradient Algorithms with Overparameterized Models

no code implementations9 Oct 2021 Arjun Ashok Rao, Hoi-To Wai

In this work, we present an empirical analysis on the performance of compressed decentralized stochastic gradient (DSG) algorithms with overparameterized NNs.

Inducing Equilibria via Incentives: Simultaneous Design-and-Play Ensures Global Convergence

no code implementations4 Oct 2021 Boyi Liu, Jiayang Li, Zhuoran Yang, Hoi-To Wai, Mingyi Hong, Yu Marco Nie, Zhaoran Wang

To regulate a social system comprised of self-interested agents, economic incentives are often required to induce a desirable outcome.

Bilevel Optimization

Detecting Central Nodes from Low-rank Excited Graph Signals via Structured Factor Analysis

no code implementations28 Sep 2021 Yiran He, Hoi-To Wai

For general low pass graph filter, we show that the graph signals can be described by a structured factor model featuring the product between a low-rank plus sparse factor and an unstructured factor.

Robust Distributed Optimization With Randomly Corrupted Gradients

no code implementations28 Jun 2021 Berkay Turan, Cesar A. Uribe, Hoi-To Wai, Mahnoosh Alizadeh

In this paper, we propose a first-order distributed optimization algorithm that is provably robust to Byzantine failures-arbitrary and potentially adversarial behavior, where all the participating agents are prone to failure.

Distributed Optimization

Tight High Probability Bounds for Linear Stochastic Approximation with Fixed Stepsize

no code implementations NeurIPS 2021 Alain Durmus, Eric Moulines, Alexey Naumov, Sergey Samsonov, Kevin Scaman, Hoi-To Wai

This family of methods arises in many machine learning tasks and is used to obtain approximate solutions of a linear system $\bar{A}\theta = \bar{b}$ for which $\bar{A}$ and $\bar{b}$ can only be accessed through random estimates $\{({\bf A}_n, {\bf b}_n): n \in \mathbb{N}^*\}$.

Vocal Bursts Intensity Prediction

Identifying First-order Lowpass Graph Signals using Perron Frobenius Theorem

no code implementations20 Jan 2021 Yiran He, Hoi-To Wai

Utilizing this observation, we develop a simple detector that answers if a given data set is produced by a first-order lowpass graph filter.

Denoising Graph Learning

Provably Efficient Neural GTD for Off-Policy Learning

no code implementations NeurIPS 2020 Hoi-To Wai, Zhuoran Yang, Zhaoran Wang, Mingyi Hong

This paper studies a gradient temporal difference (GTD) algorithm using neural network (NN) function approximators to minimize the mean squared Bellman error (MSBE).

A Stochastic Path Integral Differential EstimatoR Expectation Maximization Algorithm

no code implementations NeurIPS 2020 Gersende Fort, Eric Moulines, Hoi-To Wai

The Expectation Maximization (EM) algorithm is of key importance for inference in latent variable models including mixture of regressors and experts, missing observations.

A Stochastic Path-Integrated Differential EstimatoR Expectation Maximization Algorithm

no code implementations30 Nov 2020 Gersende Fort, Eric Moulines, Hoi-To Wai

The Expectation Maximization (EM) algorithm is of key importance for inference in latent variable models including mixture of regressors and experts, missing observations.

Geom-SPIDER-EM: Faster Variance Reduced Stochastic Expectation Maximization for Nonconvex Finite-Sum Optimization

no code implementations24 Nov 2020 Gersende Fort, Eric Moulines, Hoi-To Wai

The Expectation Maximization (EM) algorithm is a key reference for inference in latent variable models; unfortunately, its computational cost is prohibitive in the large scale learning setting.

On the Convergence of Consensus Algorithms with Markovian Noise and Gradient Bias

no code implementations18 Aug 2020 Hoi-To Wai

This rate is comparable to the best known performances of SA in a centralized setting with a non-convex potential function.

Multi-agent Reinforcement Learning

A User Guide to Low-Pass Graph Signal Processing and its Applications

no code implementations4 Aug 2020 Raksha Ramakrishna, Hoi-To Wai, Anna Scaglione

The notion of graph filters can be used to define generative models for graph data.

A Two-Timescale Framework for Bilevel Optimization: Complexity Analysis and Application to Actor-Critic

no code implementations10 Jul 2020 Mingyi Hong, Hoi-To Wai, Zhaoran Wang, Zhuoran Yang

Bilevel optimization is a class of problems which exhibit a two-level structure, and its goal is to minimize an outer objective function with variables which are constrained to be the optimal solution to an (inner) optimization problem.

Bilevel Optimization Hyperparameter Optimization

Convergence Analysis of Riemannian Stochastic Approximation Schemes

no code implementations27 May 2020 Alain Durmus, Pablo Jiménez, Éric Moulines, Salem Said, Hoi-To Wai

This paper analyzes the convergence for a large class of Riemannian stochastic approximation (SA) schemes, which aim at tackling stochastic optimization problems.

Stochastic Optimization

Finite Time Analysis of Linear Two-timescale Stochastic Approximation with Markovian Noise

no code implementations4 Feb 2020 Maxim Kaledin, Eric Moulines, Alexey Naumov, Vladislav Tadic, Hoi-To Wai

Our bounds show that there is no discrepancy in the convergence rate between Markovian and martingale noise, only the constants are affected by the mixing time of the Markov chain.

Reinforcement Learning Reinforcement Learning (RL)

Distributed Learning in the Non-Convex World: From Batch to Streaming Data, and Beyond

no code implementations14 Jan 2020 Tsung-Hui Chang, Mingyi Hong, Hoi-To Wai, Xinwei Zhang, Songtao Lu

In particular, we {provide a selective review} about the recent techniques developed for optimizing non-convex models (i. e., problem classes), processing batch and streaming data (i. e., data types), over the networks in a distributed manner (i. e., communication and computation paradigm).

Variance Reduced Policy Evaluation with Smooth Function Approximation

no code implementations NeurIPS 2019 Hoi-To Wai, Mingyi Hong, Zhuoran Yang, Zhaoran Wang, Kexin Tang

Policy evaluation with smooth and nonlinear function approximation has shown great potential for reinforcement learning.

Reinforcement Learning

On the Global Convergence of (Fast) Incremental Expectation Maximization Methods

no code implementations NeurIPS 2019 Belhal Karimi, Hoi-To Wai, Eric Moulines, Marc Lavielle

To alleviate this problem, Neal and Hinton have proposed an incremental version of the EM (iEM) in which at each iteration the conditional expectation of the latent data (E-step) is updated only for a mini-batch of observations.

Spectral partitioning of time-varying networks with unobserved edges

no code implementations26 Apr 2019 Michael T. Schaub, Santiago Segarra, Hoi-To Wai

We discuss a variant of `blind' community detection, in which we aim to partition an unobserved network from the observation of a (dynamical) graph signal defined on the network.

Community Detection

Non-asymptotic Analysis of Biased Stochastic Approximation Scheme

no code implementations2 Feb 2019 Belhal Karimi, Blazej Miasojedow, Eric Moulines, Hoi-To Wai

We illustrate these settings with the online EM algorithm and the policy-gradient method for average reward maximization in reinforcement learning.

reinforcement-learning Reinforcement Learning +1

Block-Randomized Stochastic Proximal Gradient for Low-Rank Tensor Factorization

no code implementations16 Jan 2019 Xiao Fu, Shahana Ibrahim, Hoi-To Wai, Cheng Gao, Kejun Huang

In this work, we propose a stochastic optimization framework for large-scale CPD with constraints/regularizations.

Stochastic Optimization

Low-rank Interaction with Sparse Additive Effects Model for Large Data Frames

no code implementations NeurIPS 2018 Geneviève Robin, Hoi-To Wai, Julie Josse, Olga Klopp, Éric Moulines

In this paper, we introduce a low-rank interaction and sparse additive effects (LORIS) model which combines matrix regression on a dictionary and low-rank design, to estimate main effects and interactions simultaneously.

Clustering Imputation +1

Blind Community Detection from Low-rank Excitations of a Graph Filter

no code implementations5 Sep 2018 Hoi-To Wai, Santiago Segarra, Asuman E. Ozdaglar, Anna Scaglione, Ali Jadbabaie

The paper shows that communities can be detected by applying a spectral method to the covariance matrix of graph signals.

Community Detection

Multi-Agent Reinforcement Learning via Double Averaging Primal-Dual Optimization

no code implementations NeurIPS 2018 Hoi-To Wai, Zhuoran Yang, Zhaoran Wang, Mingyi Hong

Despite the success of single-agent reinforcement learning, multi-agent reinforcement learning (MARL) remains challenging due to complex interactions between agents.

Multi-agent Reinforcement Learning reinforcement-learning +2

Accelerating Incremental Gradient Optimization with Curvature Information

1 code implementation31 May 2018 Hoi-To Wai, Wei Shi, Cesar A. Uribe, Angelia Nedich, Anna Scaglione

This paper studies an acceleration technique for incremental aggregated gradient ({\sf IAG}) method through the use of \emph{curvature} information for solving strongly convex finite sum optimization problems.

SUCAG: Stochastic Unbiased Curvature-aided Gradient Method for Distributed Optimization

no code implementations22 Mar 2018 Hoi-To Wai, Nikolaos M. Freris, Angelia Nedic, Anna Scaglione

We propose and analyze a new stochastic gradient method, which we call Stochastic Unbiased Curvature-aided Gradient (SUCAG), for finite sum optimization problems.

Distributed Optimization

Curvature-aided Incremental Aggregated Gradient Method

no code implementations24 Oct 2017 Hoi-To Wai, Wei Shi, Angelia Nedic, Anna Scaglione

We propose a new algorithm for finite sum optimization which we call the curvature-aided incremental aggregated gradient (CIAG) method.

RIDS: Robust Identification of Sparse Gene Regulatory Networks from Perturbation Experiments

no code implementations20 Dec 2016 Hoi-To Wai, Anna Scaglione, Uzi Harush, Baruch Barzel, Amir Leshem

To overcome this challenge, we develop the Robust IDentification of Sparse networks (RIDS) method that reconstructs the GRN from a small number of perturbation experiments.

Decentralized Frank-Wolfe Algorithm for Convex and Non-convex Problems

no code implementations5 Dec 2016 Hoi-To Wai, Jean Lafond, Anna Scaglione, Eric Moulines

The convergence of the proposed algorithm is studied by viewing the decentralized algorithm as an inexact FW algorithm.

Matrix Completion Sparse Learning

Active Sensing of Social Networks

no code implementations21 Jan 2016 Hoi-To Wai, Anna Scaglione, Amir Leshem

The model used for the regression is based on the steady state equation in the linear DeGroot model under the influence of stubborn agents, i. e., agents whose opinions are not influenced by their neighbors.

On the Online Frank-Wolfe Algorithms for Convex and Non-convex Optimizations

no code implementations5 Oct 2015 Jean Lafond, Hoi-To Wai, Eric Moulines

With a strongly convex stochastic cost and when the optimal solution lies in the interior of the constraint set or the constraint set is a polytope, the regret bound and anytime optimality are shown to be ${\cal O}( \log^3 T / T )$ and ${\cal O}( \log^2 T / T)$, respectively, where $T$ is the number of rounds played.

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