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Junkang Wu

17 accepted papers

2026

Causal-HalBench: Uncovering LVLMs Object Hallucinations Through Causal Intervention

AAAI 2026technical

Large Vision-Language Models (LVLMs) often suffer from object hallucination, making erroneous judgments about the presence of objects in images. We propose this primarily stems from spurious correlations arising when models strongly associate highly co-occurring objects during training, leading to h

Cited by 0SourcePDFScholar
2026

Experience Augmented Policy Optimization for LLM Reasoning

ICML 2026poster

Reinforcement Learning with Verifiable Rewards (RLVR) is a powerful paradigm for improving the reasoning capabilities of large language models (LLMs). However, existing RLVR methods typically rely on on-policy optimization from scratch, resulting in high sampling costs and inefficient utilization of…

Cited by 0SourceScholar
2026

Mitigating Reward Hacking in LLM-based Recommendation: A Preference Optimization Approach

ICML 2026poster

Post-training adaptation has become the central paradigm for leveraging large language models (LLMs) in recommendation. While recent preference optimization methods, such as Direct Preference Optimization (DPO), enhance pairwise preference discrimination, they remain vulnerable to \emph{reward hacki…

Cited by 0SourceScholar
2026

On the Direction of RLVR Updates for LLM Reasoning: Identification and Exploitation

ICLR 2026poster

Reinforcement learning with verifiable rewards (RLVR) has substantially improved the reasoning capabilities of large language models. While existing analyses identify that RLVR-induced changes are sparse, they primarily focus on the **magnitude** of these updates, largely overlooking their **direct…

Cited by 0SourcecodeScholar
2026

Quantile Advantage Estimation for Entropy-Safe Reasoning

ICLR 2026poster

Reinforcement Learning with Verifiable Rewards (RLVR) strengthens LLM reasoning but training often oscillates between {entropy collapse} and {entropy explosion}. We trace both hazards to the mean-baseline used in value-free RL (\eg GRPO/DAPO), which improperly penalizes negative-advantage samples un…

Cited by 0SourcecodeScholar
2025

AlphaDPO: Adaptive Reward Margin for Direct Preference Optimization

ICML 2025poster

Aligning large language models (LLMs) with human preferences requires balancing policy optimization with computational stability. While recent offline methods like DPO and SimPO bypass reinforcement learning’s complexity, they face critical limitations: DPO relies on static reference models that deg…

Cited by 0SourcePDFScholar
2025

DAMA: Data- and Model-aware Alignment of Multi-modal LLMs

ICML 2025poster

Direct Preference Optimization (DPO) has shown effectiveness in aligning multi-modal large language models (MLLM) with human preferences. However, existing methods exhibit an imbalanced responsiveness to the data of varying hardness, tending to overfit on the easy-to-distinguish data while underfit…

Cited by 0SourcePDFScholar
2025

LaMP-Val: Large Language Models Empower Personalized Valuation in Auction

EMNLP 2025

Auctions are a vital economic mechanism used to determine the market value of goods or services through competitive bidding within a specific framework. However, much of the current research primarily focuses on the bidding algorithms used within auction mechanisms. This often neglects the potential

2025

Larger or Smaller Reward Margins to Select Preferences for LLM Alignment?

ICML 2025poster

Preference learning is critical for aligning large language models (LLMs) with human values, with the quality of preference datasets playing a crucial role in this process. While existing metrics primarily assess data quality based on either *explicit* or *implicit* reward margins, their single-mar…

Cited by 0SourcePDFScholar
2025

MM-RLHF: The Next Step Forward in Multimodal LLM Alignment

ICML 2025poster

Existing efforts to align multimodal large language models (MLLMs) with human preferences have only achieved progress in narrow areas, such as hallucination reduction, but remain limited in practical applicability and generalizability. To this end, we introduce **MM-RLHF**, a dataset containing **12…

Cited by 13SourcePDFScholar
2025

RePO: Understanding Preference Learning Through ReLU-Based Optimization

NeurIPS 2025poster

Preference learning has become a common approach in various recent methods for aligning large language models with human values. These methods optimize the preference margin between chosen and rejected responses, subject to certain constraints for avoiding over-optimization. In this paper, we report…

Cited by 0SourceScholar
2025

Robust Preference Optimization via Dynamic Target Margins

ACL 2025finding

The alignment of Large Language Models (LLMs) is crucial for ensuring their safety and reliability in practical applications. Direct Preference Optimization (DPO) has emerged as an efficient method that directly optimizes models using preference pairs, significantly reducing resource demands. Howeve…

2025

Towards Robust Alignment of Language Models: Distributionally Robustifying Direct Preference Optimization

ICLR 2025poster

This study addresses the challenge of noise in training datasets for Direct Preference Optimization (DPO), a method for aligning Large Language Models (LLMs) with human preferences. We categorize noise into pointwise noise, which includes low-quality data points, and pairwise noise, which encompasse…

2024

$\beta$-DPO: Direct Preference Optimization with Dynamic $\beta$

NeurIPS 2024poster

Direct Preference Optimization (DPO) has emerged as a compelling approach for training Large Language Models (LLMs) to adhere to human preferences. However, the performance of DPO is sensitive to the fine-tuning of its trade-off parameter $\beta$, as well as to the quality of the preference data. We…

Cited by 0SourcePDFScholar
2024

Direct Multi-Turn Preference Optimization for Language Agents

EMNLP 2024main

Adapting Large Language Models (LLMs) for agent tasks is critical in developing language agents. Direct Preference Optimization (DPO) is a promising technique for this adaptation with the alleviation of compounding errors, offering a means to directly optimize Reinforcement Learning (RL) objectives.…

2023

Discriminative-Invariant Representation Learning for Unbiased Recommendation

IJCAI 2023poster

Selection bias hinders recommendation models from learning unbiased user preference. Recent works empirically reveal that pursuing invariant user and item representation across biased and unbiased data is crucial for counteracting selection bias. However, our theoretical analysis reveals that simply…

2023

Understanding Contrastive Learning via Distributionally Robust Optimization

NeurIPS 2023poster

This study reveals the inherent tolerance of contrastive learning (CL) towards sampling bias, wherein negative samples may encompass similar semantics (\eg labels). However, existing theories fall short in providing explanations for this phenomenon. We bridge this research gap by analyzing CL throug…