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Yifan Zeng

6 accepted papers

2025

A Common Pitfall of Margin-based Language Model Alignment: Gradient Entanglement

ICLR 2025poster

Reinforcement Learning from Human Feedback (RLHF) has become the predominant approach for aligning language models (LMs) to be more helpful and less harmful. At its core, RLHF uses a margin-based loss for preference optimization, which specifies the ideal LM behavior only in terms of the difference…

2025

Divide, Optimize, Merge: Scalable Fine-Grained Generative Optimization for LLM Agents

EMNLP 2025

LLM-based optimization has shown remarkable potential in improving agentic systems. However, the conventional approach of prompting LLM-based generative optimizer with the trajectories on the whole training dataset in a single pass becomes untenable as datasets grow, leading to context window overfl

Cited by 0SourcePDFScholar
2025

SimpleDoc: Multi‐Modal Document Understanding with Dual‐Cue Page Retrieval and Iterative Refinement

EMNLP 2025

Document Visual Question Answering (DocVQA) is a practical yet challenging task, which is to ask questions based on documents while referring to multiple pages and different modalities of information, e.g., images and tables. To handle multi-modality, recent methods follow a similar Retrieval Augmen

2025

The Ranking Blind Spot: Decision Hijacking in LLM-based Text Ranking

EMNLP 2025

Large Language Models (LLMs) have demonstrated strong performance in information retrieval tasks like passage ranking. Our research examines how instruction-following capabilities in LLMs interact with multi-document comparison tasks, identifying what we term the “Ranking Blind Spot”—a characteristi

Cited by 0SourcePDFScholar
2025

TreeBoN: Enhancing Inference-Time Alignment with Speculative Tree-Search and Best-of-N Sampling

EMNLP 2025

Inference-time alignment enhances the performance of large language models without requiring additional training or fine-tuning but presents challenges due to balancing computational efficiency with high-quality output. Best-of-N (BoN) sampling, as a simple yet powerful approach, generates multiple