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Wei Xiong

49 accepted papers

2026

EEG-FM-Bench: A Comprehensive Benchmark for the Systematic Evaluation and Diagnostic Analyses of EEG Foundation Models

ICML 2026poster

Electroencephalography foundation models (EEG-FMs) have advanced brain signal analysis, but the lack of standardized evaluation benchmarks impedes model comparison and scientific progress. Current evaluations rely on inconsistent protocols that render cross-model comparisons unreliable, while a lack…

Cited by 0SourceScholar
2026

PixelDiT: Pixel Diffusion Transformers for Image Generation

CVPR 2026

Latent-space modeling has been the standard for Diffusion Transformers (DiTs). However, it relies on a two-stage pipeline where the pretrained autoencoder introduces lossy reconstruction, leading to error accumulation while hindering joint optimization. To address these issues, we propose PixelDiT,

Cited by 0SourcecodeScholar
2025

Building Math Agents with Multi-Turn Iterative Preference Learning

ICLR 2025poster

Recent studies have shown that large language models' (LLMs) mathematical problem-solving capabilities can be enhanced by integrating external tools, such as code interpreters, and employing multi-turn Chain-of-Thought (CoT) reasoning. While current methods focus on synthetic data generation and Sup…

Cited by 24SourcePDFScholar
2025

DIVE: Taming DINO for Subject-Driven Video Editing

ICCV 2025poster

Building on the success of diffusion models in image generation and editing, video editing has recently gained substantial attention. However, maintaining temporal consistency and motion alignment still remains challenging. To address these issues, this paper proposes DINO-guided Video Editing (DIVE…

2025

DPO Meets PPO: Reinforced Token Optimization for RLHF

ICML 2025spotlight

In the classical Reinforcement Learning from Human Feedback (RLHF) framework, Proximal Policy Optimization (PPO) is employed to learn from sparse, sentence-level rewards---a challenging scenario in traditional deep reinforcement learning. Despite the great successes of PPO in the alignment of state-…

2025

EvTTC: An Event Camera Dataset for Time-to-Collision Estimation

RA-L 2025

Time-to-Collision (TTC) estimation lies in the core of the forward collision warning (FCW) functionality, which is key to all Automatic Emergency Braking (AEB) systems. Although the success of solutions using frame-based cameras (e.g., <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xli

Cited by 4SourceScholar
2025

From Lists to Emojis: How Format Bias Affects Model Alignment

ACL 2025long

In this paper, we study format biases in reinforcement learning from human feedback (RLHF). We observe that many widely-used preference models—including human evaluators, GPT-4, and top-ranking models on the RewardBench benchmark—exhibit strong biases towards specific format patterns, such as lists,…

2025

LLM Alignment as Retriever Optimization: An Information Retrieval Perspective

ICML 2025poster

Large Language Models (LLMs) have revolutionized artificial intelligence with capabilities in reasoning, coding, and communication, driving innovation across industries. Their true potential depends on effective alignment to ensure correct, trustworthy and ethical behavior, addressing challenges lik…

Cited by 1SourcePDFScholar
2025

Logarithmic Regret for Online KL-Regularized Reinforcement Learning

ICML 2025poster

Recent advances in Reinforcement Learning from Human Feedback (RLHF) have shown that KL-regularization plays a pivotal role in improving the efficiency of RL fine-tuning for large language models (LLMs). Despite its empirical advantage, the theoretical difference between KL-regularized RL and standa…

Cited by 1SourcePDFScholar
2025

MMIG-Bench: Towards Comprehensive and Explainable Evaluation of Multi-Modal Image Generation Models

NeurIPS 2025poster

Recent multimodal image generators such as GPT-4o, Gemini 2.0 Flash, and Gemini 2.5 Pro excel at following complex instructions, editing images and maintaining concept consistency. However, they are still evaluated by disjoint toolkits: text-to-image (T2I) benchmarks that lacks multi-modal condition…

Cited by 0SourceScholar
2025

MetaShadow: Object-Centered Shadow Detection, Removal, and Synthesis

CVPR 2025poster

Shadows are often underconsidered or even ignored in image editing applications, limiting the realism of the edited results. In this paper, we introduce MetaShadow, a three-in-one versatile framework that enables detection, removal, and controllable synthesis of shadows in natural images in an objec…

Cited by 2SourcePDFScholar
2025

Not All Voices Are Rewarded Equally: Probing and Repairing Reward Models across Human Diversity

EMNLP 2025

The advancement of Large Language Models (LLMs) has made ensuring their trustworthiness increasingly critical, especially in terms of fairness across diverse human groups. While modern LLMs are aligned with user preferences through Reinforcement Learning from Human Feedback (RLHF), the reward models

2025

Optimizing Chain-of-Thought Reasoners via Gradient Variance Minimization in Rejection Sampling and RL

NeurIPS 2025poster

Chain-of-thought (CoT) reasoning in large language models (LLMs) can be formalized as a latent variable problem, where the model needs to generate intermediate reasoning steps. While prior approaches such as iterative reward-ranked fine-tuning (RAFT) have relied on such formulations, they typically…

Cited by 0SourcecodeScholar
2025

RRM: Robust Reward Model Training Mitigates Reward Hacking

ICLR 2025poster

Reward models (RMs) play a pivotal role in aligning large language models (LLMs) with human preferences. However, traditional RM training, which relies on response pairs tied to specific prompts, struggles to disentangle prompt-driven preferences from prompt-independent artifacts, such as response l…

Cited by 0SourcePDFScholar
2025

Refine-by-Align: Reference-Guided Artifacts Refinement through Semantic Alignment

ICLR 2025poster

Personalized image generation has emerged from the recent advancements in generative models. However, these generated personalized images often suffer from localized artifacts such as incorrect logos, reducing fidelity and fine-grained identity details of the generated results. Furthermore, there is…

Cited by 1SourcePDFScholar
2025

polyBART: A Chemical Linguist for Polymer Property Prediction and Generative Design

EMNLP 2025

Designing polymers for targeted applications and accurately predicting their properties is a key challenge in materials science owing to the vast and complex polymer chemical space. While molecular language models have proven effective in solving analogous problems for molecular discovery, similar a

Cited by 0SourcePDFScholar
2024

Arithmetic Control of LLMs for Diverse User Preferences: Directional Preference Alignment with Multi-Objective Rewards

ACL 2024long

Fine-grained control over large language models (LLMs) remains a significant challenge, hindering their adaptability to diverse user needs. While Reinforcement Learning from Human Feedback (RLHF) shows promise in aligning LLMs, its reliance on scalar rewards often limits its ability to capture diver…

2024

Earthfarsser: Versatile Spatio-Temporal Dynamical Systems Modeling in One Model

AAAI 2024technical

Efficiently modeling spatio-temporal (ST) physical processes and observations presents a challenging problem for the deep learning community. Many recent studies have concentrated on meticulously reconciling various advantages, leading to designed models that are neither simple nor practical. To add…

2024

IMPRINT: Generative Object Compositing by Learning Identity-Preserving Representation

CVPR 2024poster

Generative object compositing emerges as a promising new avenue for compositional image editing. However the requirement of object identity preservation poses a significant challenge limiting practical usage of most existing methods. In response this paper introduces IMPRINT a novel diffusion-based…

Cited by 29SourcePDFScholar
2024

InstantBooth: Personalized Text-to-Image Generation without Test-Time Finetuning

CVPR 2024poster

Recent advances in personalized image generation have enabled pre-trained text-to-image models to learn new concepts from specific image sets. However these methods often necessitate extensive test-time finetuning for each new concept leading to inefficiencies in both time and scalability. To addres…

Cited by 272SourcePDFScholar
2024

Interpretable Preferences via Multi-Objective Reward Modeling and Mixture-of-Experts

EMNLP 2024finding

Reinforcement learning from human feedback (RLHF) has emerged as the primary method for aligning large language models (LLMs) with human preferences. The RLHF process typically starts by training a reward model (RM) using human preference data. Conventional RMs are trained on pairwise responses to t…

2024

Iterative Preference Learning from Human Feedback: Bridging Theory and Practice for RLHF under KL-constraint

ICML 2024poster

This paper studies the theoretical framework of the alignment process of generative models with Reinforcement Learning from Human Feedback (RLHF). We consider a standard mathematical formulation, the reverse-KL regularized contextual bandit for RLHF. Despite its widespread practical application, a r…

Cited by 139SourcePDFScholar
2024

LMFlow: An Extensible Toolkit for Finetuning and Inference of Large Foundation Models

NAACL 2024system demonstrations

Foundation models have demonstrated a great ability to achieve general human-level intelligence far beyond traditional approaches. As the technique keeps attracting attention from the AI community, more and more foundation models have become publicly available.However, most of those models exhibit a…

2024

Mitigating the Alignment Tax of RLHF

EMNLP 2024main

LLMs acquire a wide range of abilities during pre-training, but aligning LLMs under Reinforcement Learning with Human Feedback (RLHF) can lead to forgetting pretrained abilities, which is also known as the alignment tax. To investigate alignment tax, we conducted experiments with existing RLHF algor…

2024

Online Iterative Reinforcement Learning from Human Feedback with General Preference Model

NeurIPS 2024poster

We investigate Reinforcement Learning from Human Feedback (RLHF) in the context of a general preference oracle. In particular, we do not assume the existence of a reward function and an oracle preference signal drawn from the Bradley-Terry model as most of the prior works do. We consider a standard…

2024

Relightful Harmonization: Lighting-aware Portrait Background Replacement

CVPR 2024poster

Portrait harmonization aims to composite a subject into a new background adjusting its lighting and color to ensure harmony with the background scene. Existing harmonization techniques often only focus on adjusting the global color and brightness of the foreground and ignore crucial illumination cue…

Cited by 15SourcePDFScholar
2024

Strengthening Multimodal Large Language Model with Bootstrapped Preference Optimization

ECCV 2024oral

"Multimodal Large Language Models (MLLMs) excel in generating responses based on visual inputs. However, they often suffer from a bias towards generating responses similar to their pretraining corpus, overshadowing the importance of visual information. We treat this bias as a “preference” for pretra…

2024

SwapAnything: Enabling Arbitrary Object Swapping in Personalized Image Editing

ECCV 2024poster

"Effective editing of personal content holds a pivotal role in enabling individuals to express their creativity, weaving captivating narratives within their visual stories, and elevate the overall quality and impact of their visual content. Therefore, in this work, we introduce , a novel framework t…

Cited by 16SourcePDFScholar
2024

WAS: Dataset and Methods for Artistic Text Segmentation

ECCV 2024poster

"Accurate text segmentation results are crucial for text-related generative tasks, such as text image generation, text editing, text removal, and text style transfer. Recently, some scene text segmentation methods have made significant progress in segmenting regular text. However, these methods perf…

2023

Corruption-Robust Algorithms with Uncertainty Weighting for Nonlinear Contextual Bandits and Markov Decision Processes

ICML 2023poster

Despite the significant interest and progress in reinforcement learning (RL) problems with adversarial corruption, current works are either confined to the linear setting or lead to an undesired $\tilde{\mathcal O}(\sqrt{T}\zeta)$ regret bound, where $T$ is the number of rounds and $\zeta$ is the to…

Cited by 29SourcePDFScholar
2023

Maximize to Explore: One Objective Function Fusing Estimation, Planning, and Exploration

NeurIPS 2023spotlight

In reinforcement learning (RL), balancing exploration and exploitation is crucial for achieving an optimal policy in a sample-efficient way. To this end, existing sample- efficient algorithms typically consist of three components: estimation, planning, and exploration. However, to cope with general…

2023

Nearly Minimax Optimal Offline Reinforcement Learning with Linear Function Approximation: Single-Agent MDP and Markov Game

ICLR 2023poster

Offline reinforcement learning (RL) aims at learning an optimal strategy using a pre-collected dataset without further interactions with the environment. While various algorithms have been proposed for offline RL in the previous literature, the minimax optimality has only been (nearly) established f…

Cited by 54SourcePDFScholar
2023

PHOTOSWAP: Personalized Subject Swapping in Images

NeurIPS 2023poster

In an era where images and visual content dominate our digital landscape, the ability to manipulate and personalize these images has become a necessity. Envision seamlessly substituting a tabby cat lounging on a sunlit window sill in a photograph with your own playful puppy, all while preserving the…

Cited by 36SourcePDFScholar
2023

Provably Efficient Offline Reinforcement Learning with Perturbed Data Sources

ICML 2023poster

Existing theoretical studies on offline reinforcement learning (RL) mostly consider a dataset sampled directly from the target task. In practice, however, data often come from several heterogeneous but related sources. Motivated by this gap, this work aims at rigorously understanding offline RL with…

Cited by 4SourcePDFScholar
2022

A Self-Play Posterior Sampling Algorithm for Zero-Sum Markov Games

ICML 2022spotlight

Existing studies on provably efficient algorithms for Markov games (MGs) almost exclusively build on the “optimism in the face of uncertainty” (OFU) principle. This work focuses on a distinct approach of posterior sampling, which is celebrated in many bandits and reinforcement learning settings but…

Cited by 25SourcePDFScholar
2022

Pessimistic Minimax Value Iteration: Provably Efficient Equilibrium Learning from Offline Datasets

ICML 2022spotlight

We study episodic two-player zero-sum Markov games (MGs) in the offline setting, where the goal is to find an approximate Nash equilibrium (NE) policy pair based on a dataset collected a priori. When the dataset does not have uniform coverage over all policy pairs, finding an approximate NE involves…

Cited by 52SourcePDFScholar
2021

(Almost) Free Incentivized Exploration from Decentralized Learning Agents

NeurIPS 2021poster

Incentivized exploration in multi-armed bandits (MAB) has witnessed increasing interests and many progresses in recent years, where a principal offers bonuses to agents to do explorations on her behalf. However, almost all existing studies are confined to temporary myopic agents. In this work, we br…

2021

An Accuracy Network Anomaly Detection Method Based on Ensemble Model

ICASSP 2021accepted

Identifying network anomaly detection is important since they may carry critical information in circumstances such as a burst of intrusions, privacy theft, system damage and fraudulent activities. In recent years, there are many detection methods for network anomalies are proposed, however, a single…

Cited by 0SourceScholar
2021

Distributional Reinforcement Learning for Multi-Dimensional Reward Functions

NeurIPS 2021poster

A growing trend for value-based reinforcement learning (RL) algorithms is to capture more information than scalar value functions in the value network. One of the most well-known methods in this branch is distributional RL, which models return distribution instead of scalar value. In another line of…

2021

Heterogeneous Multi-player Multi-armed Bandits: Closing the Gap and Generalization

NeurIPS 2021poster

Despite the significant interests and many progresses in decentralized multi-player multi-armed bandits (MP-MAB) problems in recent years, the regret gap to the natural centralized lower bound in the heterogeneous MP-MAB setting remains open. In this paper, we propose BEACON -- Batched Exploration w…

2020

Decentralized Multi-player Multi-armed Bandits with No Collision Information

AISTATS 2020poster

The decentralized stochastic multi-player multi-armed bandit (MP-MAB) problem, where the collision information is not available to the players, is studied in this paper. Building on the seminal work of Boursier and Perchet (2019), we propose error correction synchronization involving communication (…

Cited by 45SourcePDFScholar
2020

Example-Guided Image Synthesis using Masked Spatial-Channel Attention and Self-Supervision

ECCV 2020poster

Example-guided image synthesis has recently been attempted to synthesize an image from a semantic label map and an exemplary image. In the task, the additional exemplar image provides the style guidance that controls the appearance of the synthesized output. Despite the controllability advantage, th…

Cited by 22SourcePDFScholar
2020

Fine-Grained Image-to-Image Transformation Towards Visual Recognition

CVPR 2020poster

Existing image-to-image transformation approaches primarily focus on synthesizing visually pleasing data. Generating images with correct identity labels is challenging yet much less explored. It is even more challenging to deal with image transformation tasks with large deformation in poses, viewpoi…

Cited by 35PDFScholar
2018

Focus, Segment and Erase: An Efficient Network for Multi-Label Brain Tumor Segmentation

ECCV 2018poster

In multi-label brain tumor segmentation, class imbalance and inter-class interference are common and challenging problems. In this paper, we propose a novel end-to-end trainable network named FSENet to address the aforementioned issues. The proposed FSENet has a tumor region pooling component to res…

Cited by 68SourcePDFScholar
2018

Learning to Generate Time-Lapse Videos Using Multi-Stage Dynamic Generative Adversarial Networks

CVPR 2018poster

Taking a photo outside, can we predict the immediate future, e.g., how would the cloud move in the sky? We address this problem by presenting a generative adversarial network (GAN) based two-stage approach to generating realistic time-lapse videos of high resolution. Given the first frame, our model…

Cited by 209SourcePDFScholar
2018

Toeplitz Matrix-Based Transmit Covariance Matrix of Colocated Mimo Radar Waveforms for Sinr Maximization

ICASSP 2018accepted

Focusing on the signal-to interference-plus-noise ratio (SINR) maximization in colocated multiple-input multiple-output (MIMO) radars, using the covariance matrix design of transmitted waveforms, we propose a kind of transmit covariance matrix (TCM) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML…

Cited by 0SourceScholar
2015

Underwater electric current communication of robotic fish: Design and experimental results

ICRA 2015poster

Communication is challenging for underwater robots. This paper presents the first research into developing an underwater electric current communication system and integrating the system into a small robotic fish. It is notable for its potential for a group of underwater robots communicating within a…

Cited by 34SourceScholar