Sean Du
Author directory2026
VAUQ: Vision-Aware Uncertainty Quantification for LVLM Self-Evaluation
Seongheon Park | Changdae Oh | Hyeong Kyu Choi | Sean Du | Sharon Li
Findings of the Association for Computational Linguistics: ACL 2026
Seongheon Park | Changdae Oh | Hyeong Kyu Choi | Sean Du | Sharon Li
Findings of the Association for Computational Linguistics: ACL 2026
Large Vision-Language Models (LVLMs) frequently hallucinate, limiting their safe deployment in real-world applications. Existing LLM self-evaluation methods rely on a model’s ability to estimate the correctness of its own outputs, which can improve deployment reliability; however, they depend heavily on language priors and are therefore ill-suited for evaluating vision-conditioned predictions. We propose VAUQ, a vision-aware uncertainty quantification framework for LVLM self-evaluation that explicitly measures how strongly a model’s output depends on visual evidence. VAUQ introduces the Image-Information Score (IS), which captures the reduction in predictive uncertainty attributable to visual input, and an unsupervised core-region masking strategy that amplifies the influence of salient regions. Combining predictive entropy with this core-masked IS yields a training-free scoring function that reliably reflects answer correctness. Comprehensive experiments show that VAUQ consistently outperforms existing self-evaluation methods across multiple datasets.
Deeper is Not Always Better: Mitigating the Alignment Tax via Confident Layer Decoding
Sining Zhoubian | Xuanming Zhang | Yuxuan Chen | Tianyi Tang | An Yang | Sean Du | Chujie Zheng | Fei Huang | Dayiheng Liu | Gao Huang | Jingren Zhou
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Sining Zhoubian | Xuanming Zhang | Yuxuan Chen | Tianyi Tang | An Yang | Sean Du | Chujie Zheng | Fei Huang | Dayiheng Liu | Gao Huang | Jingren Zhou
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Autoregressive generation in large language models (LLMs) conventionally decodes from the final layer, assuming that deeper representations yield more reliable next-token predictions. We revisit this assumption by revealing a recurring **Guess–Refine–Perturb** dynamic: early layers form coarse guesses, intermediate layers refine reasoning-relevant semantics, and final layers can perturb these refined predictions toward generic or alignment-preferred tokens. We introduce **Confident Decoding**, a training-free decoding strategy that dynamically selects a near-final layer through entropy-guided conservative backward search. We further formulate layer selection as an optimal stopping problem and show that, under explicit local-monotonicity and bounded-probe-noise conditions, the search rule filters terminal perturbations while bounding unfinished refinement. Experiments across dense and Mixture-of-Experts LLMs show that gains concentrate on challenging reasoning settings, including GPQA-Diamond, Omni-MATH, and HLE, while saturated tasks remain broadly stable, with no additional KV-cache memory and less than 2% latency increase. These results suggest dynamically bypassing final-layer perturbations can recover stronger reasoning behavior from aligned LLMs.
Uncertainty Quantification in LLM Agents: Foundations, Emerging Challenges, and Opportunities
Changdae Oh | Seongheon Park | To Eun Kim | Jiatong Li | Wendi Li | Samuel Yeh | Sean Du | Hamed Hassani | Paul Bogdan | Dawn Song | Sharon Li
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Changdae Oh | Seongheon Park | To Eun Kim | Jiatong Li | Wendi Li | Samuel Yeh | Sean Du | Hamed Hassani | Paul Bogdan | Dawn Song | Sharon Li
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Uncertainty quantification (UQ) for large language models (LLMs) is a key building block for safety guardrails of daily LLM applications. Yet, even as LLM agents are increasingly deployed in highly complex tasks, most UQ research still centers on single-turn question-answering. We argue that UQ research must shift to realistic settings with interactive agents, and that a new principled framework for agent UQ is needed. This paper presents three pillars to build a solid ground for future agent UQ research: (1. Foundations) We present the first general formulation of agent UQ that subsumes broad classes of existing UQ setups; (2. Challenges) We identify four technical challenges specifically tied to agentic setups—selection of uncertainty estimator, uncertainty of heterogeneous entities, modeling uncertainty dynamics in interactive systems, and lack of fine-grained benchmarks—with numerical analysis on a real-world agent benchmark, 𝜏2-bench; (3. Future Directions) We conclude with noting on the practical implications of agent UQ and remaining open problems as forward-looking discussion for future explorations.