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Noah Lee

9 accepted papers

2026

Margin-Aware Preference Optimization for Aligning Diffusion Models Without Reference

AAAI 2026technical

Modern preference alignment methods, such as DPO, rely on divergence regularization to a reference model for training stability—but this creates a fundamental problem we call "reference mismatch." In this paper, we investigate the negative impacts of reference mismatch in aligning text-to-image (T2I

Cited by 0SourcePDFScholar
2025

AlphaPO: Reward Shape Matters for LLM Alignment

ICML 2025poster

Reinforcement Learning with Human Feedback (RLHF) and its variants have made huge strides toward the effective alignment of large language models (LLMs) to follow instructions and reflect human values. More recently, Direct Alignment Algorithms (DAAs) have emerged in which the reward modeling stage…

Cited by 0SourcePDFScholar
2025

Cross-lingual Transfer of Reward Models in Multilingual Alignment

NAACL 2025short

Reinforcement learning with human feedback (RLHF) is shown to largely benefit from precise reward models (RMs). However, recent studies in reward modeling schemes are skewed towards English, limiting the applicability of RLHF in multilingual alignments. In this work, we investigate the cross-lingual…

2025

On the Robustness of Reward Models for Language Model Alignment

ICML 2025poster

The Bradley-Terry (BT) model is widely practiced in reward modeling for reinforcement learning with human feedback (RLHF). Despite its effectiveness, reward models (RMs) trained with BT model loss as one-way classifiers are prone to over-optimization, losing generalizability to unseen inputs. In thi…

Cited by 0SourcePDFScholar
2025

The BiGGen Bench: A Principled Benchmark for Fine-grained Evaluation of Language Models with Language Models

NAACL 2025long

As language models (LMs) become capable of handling a wide range of tasks, their evaluation is becoming as challenging as their development. Most generation benchmarks currently assess LMs using abstract evaluation criteria-like helpfulness and harmlessness-which often lack the flexibility and granu…