Tun Lu
Author directory2026
StreamMemBench: Streaming Evaluation of Agent Memory for Future-Oriented Assistance
Guanming Liu | Yuqi Ren | Hansu Gu | Peng Zhang | Weihang Wang | Jiahao Liu | Ning Gu | Tun Lu
Findings of the Association for Computational Linguistics: EMNLP 2026
Guanming Liu | Yuqi Ren | Hansu Gu | Peng Zhang | Weihang Wang | Jiahao Liu | Ning Gu | Tun Lu
Findings of the Association for Computational Linguistics: EMNLP 2026
A central role of personal-agent memory is to turn stored information and prior interactions into future-oriented assistance. In daily use, useful cues come from what the agent observes and how the user interacts with the agent, and the agent must carry them forward from the current request to similar future tasks. Existing memory benchmarks usually test dialogue recall or task improvement in isolation, leaving the trajectory from streaming observations to later assistance largely untested. We introduce StreamMemBench, a streaming benchmark that constructs a two-step task sequence around each evidence anchor from EgoLife egocentric streams. The initial task tests evidence use, while the follow-up task tests whether feedback and interaction experience are reused. Four metrics diagnose evidence recall, initial evidence use, feedback incorporation, and follow-up reuse. Experiments with eight memory systems across two backbones show that current systems often fail to use observed evidence or turn feedback into reliable follow-up behavior, even when evidence is stored or feedback is incorporated locally.
Fast-Slow Thinking RM: Efficient Integration of Scalar and Generative Reward Models
Jiayun Wu | Peng Zhang | Yuanyuan Lu | Shan Qu | Ning Gu | Tun Lu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Jiayun Wu | Peng Zhang | Yuanyuan Lu | Shan Qu | Ning Gu | Tun Lu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Reward models (RMs) are critical for aligning Large Language Models via Reinforcement Learning from Human Feedback (RLHF). While Generative Reward Models (GRMs) achieve superior accuracy through chain-of-thought (CoT) reasoning, they incur substantial computational costs. Conversely, Scalar Reward Models (SRMs) offer efficiency but suffer from limited performance and adaptability in complex scenarios. We introduce Fast-Slow Thinking Reward Models (F/S-RM), a hybrid RM architecture inspired by Dual Process Theory. It trains a single model to integrate two distinct reward paradigms: scalar-style first-token pairwise judgment (fast thinking) and CoT-based judgment (slow thinking), regulated by a dual-confidence activation mechanism that determines when to activate slow thinking. Under hybrid inference, F/S-RM achieves state-of-the-art accuracy with an average score of 84.3 across benchmarks, while reducing token consumption by 22.5%. Code and data are publicly available.
VIRA-Bench: Diagnosing Pedagogical Contingency Understanding in Online Tutoring Videos
Weihang Wang | Hansu Gu | Guanming Liu | Peng Zhang | Ning Gu | Tun Lu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Weihang Wang | Hansu Gu | Guanming Liu | Peng Zhang | Ning Gu | Tun Lu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Understanding online tutoring requires more than recognizing isolated events. A model must connect what a teacher says or does to how the learner responds and how the teacher subsequently adapts. Existing video benchmarks emphasize event and temporal understanding, while educational-dialogue benchmarks are largely transcript-based, leaving this interactional contingency underexplored. We introduce VIRA-Bench, a diagnostic benchmark for short-horizon pedagogical contingency in one-to-one tutoring videos. Grounded in the Initiation–Response–Follow-up structure and contingent teaching theory, VIRA-Bench contains 1,005 clips and 1,322 multiple-choice questions organized into three layers: Observable Evidence Grounding, Interaction Contingency Reasoning, and Support-Response Modeling. Items are built through researcher-led evidence auditing and expert verification to keep questions tied to observable interaction evidence. Across 11 multimodal large language models, the best model reaches 61.3% accuracy, compared with 91.0% on a stratified human subset, with interaction contingency reasoning emerging as the most consistent weakness. Controlled evidence interventions reveal distinct dependencies across layers. Removing video hurts observable grounding most, while disrupting interaction order hurts contingency reasoning most. Additional controls show that this distinction survives free-response evaluation and cannot be explained by question-option shortcuts or video–transcript misalignment. By separating visual grounding from order-sensitive interaction reasoning, VIRA-Bench exposes diagnostic differences that aggregate video-QA scores obscure.
LLMs for Now, Fine-Tuning for Later: An Ensemble Approach to Data Drift in Domain-Specific Tasks
Yuxuan Lu | Bingsheng Yao | Shao Zhang | Yisi Sang | Yun Wang | Hansu Gu | Peng Zhang | Tun Lu | Toby Jia-Jun Li | Dakuo Wang
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 4: Student Research Workshop)
Yuxuan Lu | Bingsheng Yao | Shao Zhang | Yisi Sang | Yun Wang | Hansu Gu | Peng Zhang | Tun Lu | Toby Jia-Jun Li | Dakuo Wang
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 4: Student Research Workshop)
Deploying machine learning models in real-world domain-specific scenarios is challenged by the scarcity of expert annotations and by data drift, where the statistical properties of incoming data continuously evolve. Active Learning (AL) iteratively improves compact models with expert annotations but suffers from recurring cold-start degradation, while LLMs provide strong off-the-shelf performance yet cannot leverage newly accumulated labels, raising the question: how can we better leverage LLMs to assist the active learning process? Through an empirical study on five legal and biomedical datasets, we reveal a complementary temporal dynamic: LLMs excel during early and post-drift stages, while AL-assisted compact models eventually surpass them as annotations accumulate. Motivated by this finding, we propose an ensemble system that combines an LLM, an AL-assisted compact model, and an automatic switch module that routes predictions to the better-performing model in real time. Evaluated under simulated data drift on two mental health datasets, our system achieves 96–98% switch accuracy and consistently outperforms either model used alone.
2025
Value Compass Benchmarks: A Comprehensive, Generative and Self-Evolving Platform for LLMs’ Value Evaluation
Jing Yao | Xiaoyuan Yi | Shitong Duan | Jindong Wang | Yuzhuo Bai | Muhua Huang | Yang Ou | Scarlett Li | Peng Zhang | Tun Lu | Zhicheng Dou | Maosong Sun | James Evans | Xing Xie
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 3: System Demonstrations)
Jing Yao | Xiaoyuan Yi | Shitong Duan | Jindong Wang | Yuzhuo Bai | Muhua Huang | Yang Ou | Scarlett Li | Peng Zhang | Tun Lu | Zhicheng Dou | Maosong Sun | James Evans | Xing Xie
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 3: System Demonstrations)
As large language models (LLMs) are gradually integrated into human daily life, assessing their underlying values becomes essential for understanding their risks and alignment with specific preferences. Despite growing efforts, current value evaluation methods face two key challenges. C1. Evaluation Validity: Static benchmarks fail to reflect intended values or yield informative results due to data contamination or a ceiling effect. C2. Result Interpretation: They typically reduce the pluralistic and often incommensurable values to one-dimensional scores, which hinders users from gaining meaningful insights and guidance. To address these challenges, we present Value Compass Benchmarks, the first dynamic, online and interactive platform specially devised for comprehensive value diagnosis of LLMs. It (1) grounds evaluations in multiple basic value systems from social science; (2) develops a generative evolving evaluation paradigm that automatically creates real-world test items co-evolving with ever-advancing LLMs; (3) offers multi-faceted result interpretation, including (i) fine-grained scores and case studies across 27 value dimensions for 33 leading LLMs, (ii) customized comparisons, and (iii) visualized analysis of LLMs’ alignment with cultural values. We hope Value Compass Benchmarks serves as a navigator for further enhancing LLMs’ safety and alignment, benefiting their responsible and adaptive development.
2024
Negating Negatives: Alignment with Human Negative Samples via Distributional Dispreference Optimization
Shitong Duan | Xiaoyuan Yi | Peng Zhang | Yan Liu | Zheng Liu | Tun Lu | Xing Xie | Ning Gu
Findings of the Association for Computational Linguistics: EMNLP 2024
Shitong Duan | Xiaoyuan Yi | Peng Zhang | Yan Liu | Zheng Liu | Tun Lu | Xing Xie | Ning Gu
Findings of the Association for Computational Linguistics: EMNLP 2024
Large language models (LLMs) have revolutionized the role of AI, yet pose potential social risks. To steer LLMs towards human preference, alignment technologies have been introduced and gained increasing attention. Nevertheless, existing methods heavily rely on high-quality positive-negative training pairs, suffering from noisy positive responses that are barely distinguishable from negative ones. Given recent LLMs’ proficiency in generating helpful responses, this work pivots towards a new research question: can we achieve alignment using solely human-annotated negative samples, preserving helpfulness while reducing harmfulness? For this purpose, we propose Distributional Dispreference Optimization (D2O), which maximizes the discrepancy between dispreferred responses and the generated non-negative ones. In this way, D2O effectively eschews harmful information without incorporating noisy positive samples, while avoiding collapse using self-generated responses as anchors. We demonstrate that D2O can be regarded as learning a distributional preference model reflecting human dispreference against negative responses, which is theoretically an upper bound of the instance-level DPO. Extensive experiments manifest that our method achieves comparable generation quality and surpasses the latest strong baselines in producing less harmful and more informative responses with better training stability and faster convergence.
2023
An Intent-based and Annotation-free Method for Duplicate Question Detection in CQA Forums
Yubo Shu | Hansu Gu | Peng Zhang | Tun Lu | Ning Gu
Findings of the Association for Computational Linguistics: EMNLP 2023
Yubo Shu | Hansu Gu | Peng Zhang | Tun Lu | Ning Gu
Findings of the Association for Computational Linguistics: EMNLP 2023
With the advent of large language models (LLMs), Community Question Answering (CQA) forums offer well-curated questions and answers that can be utilized for instruction-tuning, effectively training LLMs to be aligned with human intents. However, the issue of duplicate questions arises as the volume of content within CQA continues to grow, posing a threat to content quality. Recent research highlights the benefits of detecting and eliminating duplicate content. It not only enhances the LLMs’ ability to generalize across diverse intents but also improves the efficiency of training data utilization while addressing concerns related to information leakage. However, existing methods for detecting duplicate questions in CQA typically rely on generic text-pair matching models, overlooking the intent behind the questions. In this paper, we propose a novel intent-based duplication detector named Intent-DQD that comprehensively leverages intent information to address the problem of duplicate question detection in CQA. Intent-DQD first leverages the characteristics in CQA forums and extracts training labels to recognize and match intents without human annotation. Intent-DQD then effectively aggregates intent-level relations and establishes question-level relations to enable intent-aware duplication detection. Experimental results on fifteen distinct domains from both CQADupStack and Stack Overflow datasets demonstrate the effectiveness of Intent-DQD. Reproducible codes and datasets will be released upon publication of the paper.
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Co-authors
- Ning Gu 5
- Peng Zhang 5
- Hansu Gu 4
- Shitong Duan 2
- Guanming Liu 2
- Weihang Wang 2
- Xing Xie 2
- Xiaoyuan Yi 2
- Peng Zhang 2
- Yuzhuo Bai 1
- Zhicheng Dou (窦志成) 1
- James Evans 1
- Muhua Huang 1
- Scarlett Li 1
- Toby Jia-Jun Li 1
- Jiahao Liu 1
- Yan Liu 1
- Zheng Liu 1
- Yuanyuan Lu 1
- Yuxuan Lu 1
- Yang Ou 1
- Shan Qu 1
- Yuqi Ren 1
- Yisi Sang 1
- Yubo Shu 1
- Maosong Sun (孙茂松) 1
- Dakuo Wang 1
- Jindong Wang 1
- Yun Wang 1
- Jiayun Wu 1
- Bingsheng Yao 1
- Jing Yao 1
- Shao Zhang 1