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Haoxian Chen

8 accepted papers

2026

TokUR: Token-Level Uncertainty Estimation for Large Language Model Reasoning

ICLR 2026poster

While Large Language Models (LLMs) have demonstrated impressive capabilities, their output quality remains inconsistent across various application scenarios, making it difficult to identify trustworthy responses, especially in complex tasks requiring multi-step reasoning. In this paper, we propose a…

Cited by 0SourcecodeScholar
2026

VMonarch: Efficient Video Diffusion Transformers with Structured Attention

CVPR 2026

The quadratic complexity of the attention mechanism severely limits the context scalability of Video Diffusion Transformers (DiTs). We find that the highly sparse spatio-temporal attention patterns exhibited in Video DiTs can be naturally represented by the Monarch matrix. It is a class of structure

Cited by 2SourceScholar
2025

MallowsPO: Fine-Tune Your LLM with Preference Dispersions

ICLR 2025poster

Direct Preference Optimization (DPO) has recently emerged as a popular approach to improve reinforcement learning from human feedback (RLHF), leading to better techniques to fine-tune large language models (LLM). A weakness of DPO, however, lies in its lack of capability to characterize the diversit…

Cited by 6SourcePDFScholar
2025

Score as Action: Fine Tuning Diffusion Generative Models by Continuous-time Reinforcement Learning

ICML 2025poster

Reinforcement learning from human feedback (RLHF), which aligns a diffusion model with input prompt, has become a crucial step in building reliable generative AI models. Most works in this area uses a *discrete-time* formulation, which is prone to induced errors, and often not applicable to models w…

Cited by 1SourcePDFScholar
2022

From block-Toeplitz matrices to differential equations on graphs: towards a general theory for scalable masked Transformers

ICML 2022spotlight

In this paper we provide, to the best of our knowledge, the first comprehensive approach for incorporating various masking mechanisms into Transformers architectures in a scalable way. We show that recent results on linear causal attention (Choromanski et al., 2021) and log-linear RPE-attention (Luo…

2022

Hybrid Random Features

ICLR 2022poster

We propose a new class of random feature methods for linearizing softmax and Gaussian kernels called hybrid random features (HRFs) that automatically adapt the quality of kernel estimation to provide most accurate approximation in the defined regions of interest. Special instantiations of HRFs lead…

2021

Learning Prediction Intervals for Regression: Generalization and Calibration

AISTATS 2021poster

We study the generation of prediction intervals in regression for uncertainty quantification. This task can be formalized as an empirical constrained optimization problem that minimizes the average interval width while maintaining the coverage accuracy across data. We strengthen the existing literat…

Cited by 27SourcePDFScholar
2020

Demystifying Orthogonal Monte Carlo and Beyond

NeurIPS 2020poster

Orthogonal Monte Carlo (OMC) is a very effective sampling algorithm imposing structural geometric conditions (orthogonality) on samples for variance reduction. Due to its simplicity and superior performance as compared to its Quasi Monte Carlo counterparts, OMC is used in a wide spectrum of challeng…