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Zexu Sun

12 accepted papers

2026

Beyond Step Pruning: Information Theory Based Step-level Optimization for Self-Refining Large Language Models

AAAI 2026technical

Large language models (LLMs) have shown impressive capabilities in natural language tasks, yet they continue to struggle with multi-step mathematical reasoning, where correctness depends on a precise chain of intermediate steps. Preference optimization methods such as Direct Preference Optimization

Cited by 0SourcePDFScholar
2026

CurES: From Gradient Analysis to Efficient Curriculum Learning for Reasoning LLMs

ICLR 2026poster

Curriculum learning plays a crucial role in enhancing the training efficiency of large language models (LLMs) on reasoning tasks. However, existing methods often fail to adequately account for variations in prompt difficulty or rely on simplistic filtering mechanisms to select prompt datasets within…

Cited by 0SourcecodeScholar
2026

Prompt and Parameter Co-Optimization for Large Language Models

ICLR 2026poster

Prompt optimization and fine-tuning are two major approaches to improve the performance of Large Language Models (LLMs). They enhance the capabilities of LLMs from complementary perspectives: the former through explicit natural language, and the latter through implicit parameter updates. However, p…

Cited by 0SourceScholar
2026

Solving the Granularity Mismatch: Hierarchical Preference Learning for Long-Horizon LLM Agents

ICLR 2026poster

Large Language Models (LLMs) as autonomous agents are increasingly tasked with solving complex, long-horizon problems. Aligning these agents via preference-based methods like Direct Preference Optimization (DPO) is a promising direction, yet it faces a critical granularity mismatch. Trajectory-lev…

Cited by 0SourceScholar
2025

Invariant Deep Uplift Modeling for Incentive Assignment in Online Marketing via Probability of Necessity and Sufficiency

ICML 2025spotlight

In online platforms, incentives (\textit{e.g}., discounts, coupons) are used to boost user engagement and revenue. Uplift modeling methods are developed to estimate user responses from observational data, often incorporating distribution balancing to address selection bias. However, these methods ar…

Cited by 0SourcePDFScholar
2025

KAPA: A Deliberative Agent Framework with Tree-Structured Knowledge Base for Multi-Domain User Intent Understanding

ACL 2025finding

Dialogue assistants have become ubiquitous in modern applications, fundamentally reshaping human daily communication patterns and information access behaviors. In real-world conversational interactions, however, user queries are often volatile, ambiguous, and diverse, making it difficult accurately…

Cited by 0SourcePDFScholar
2025

Learning to Focus: Causal Attention Distillation via Gradient‐Guided Token Pruning

NeurIPS 2025poster

Large language models (LLMs) have demonstrated significant improvements in contextual understanding. However, their ability to attend to truly critical information during long-context reasoning and generation still falls behind the pace. Specifically, our preliminary experiments reveal that certain…

Cited by 0SourceScholar
2025

Rethinking Causal Ranking: A Balanced Perspective on Uplift Model Evaluation

ICML 2025poster

Uplift modeling is crucial for identifying individuals likely to respond to a treatment in applications like marketing and customer retention, but evaluating these models is challenging due to the inaccessibility of counterfactual outcomes in real-world settings. In this paper, we identify a fundame…

2025

Uncertainty and Influence aware Reward Model Refinement for Reinforcement Learning from Human Feedback

ICLR 2025poster

Reinforcement Learning from Human Feedback (RLHF) has emerged as a standard and effective approach for training large language models (LLMs) with human preferences. In this framework, a learned reward model approximates human preferences and guides policy optimization, making it crucial to develop a…

Cited by 1SourcePDFScholar
2024

Controllable Preference Optimization: Toward Controllable Multi-Objective Alignment

EMNLP 2024main

Alignment in artificial intelligence pursues the consistency between model responses and human preferences as well as values. In practice, the multifaceted nature of human preferences inadvertently introduces what is known as the ”alignment tax”–a compromise where enhancements in alignment within on…

2023

Offline Imitation Learning with Variational Counterfactual Reasoning

NeurIPS 2023poster

In offline imitation learning (IL), an agent aims to learn an optimal expert behavior policy without additional online environment interactions. However, in many real-world scenarios, such as robotics manipulation, the offline dataset is collected from suboptimal behaviors without rewards. Due to th…