Guanzhen Li
Author directory2026
ProEvent: An Event-centric Benchmark for Proactive Agents
Guanzhen Li | Liangming Pan | Leye Wang
Findings of the Association for Computational Linguistics: EMNLP 2026
Guanzhen Li | Liangming Pan | Leye Wang
Findings of the Association for Computational Linguistics: EMNLP 2026
Proactive agents are expected to anticipate user needs and provide autonomous assistance by perceiving environmental context without explicit instructions. A fundamental capability of such agents is to identify and track users’ upcoming events, enabling continuous and event-specific assistance. For example, by recording the time and location of a planned hike, an agent can deliver weather reminders in advance or provide navigation support before departure. However, existing works on proactive agents largely overlook event-centric assistance, and the open-ended nature of proactive assistance poses challenges for reliable evaluation.
To bridge these gaps, we introduce ProEvent, the first event-centric benchmark designed to assess an agent’s ability to proactively maintain a user’s timetable based on ongoing instant messaging chats. ProEvent provides synthesized yet realistic chats that consider the dynamic interaction among users, concurrent chat threads, and noise in the real world, and evaluates proactive agents on response timing, single-step response correctness, and multi-step response correctness. Experiments on eight LLMs and pipelines reveal that current agents frequently overact and struggle with event cancellation. Notably, even the state-of-the-art GPT-5.1 provides redundant assistance in 30% of cases and achieves only 26.7% recall in event cancellation scenarios. Further qualitative analysis reveals fundamental limitations of current LLMs as proactive agents, particularly in detecting implicit events and reasoning from the user’s first-person perspective.
To bridge these gaps, we introduce ProEvent, the first event-centric benchmark designed to assess an agent’s ability to proactively maintain a user’s timetable based on ongoing instant messaging chats. ProEvent provides synthesized yet realistic chats that consider the dynamic interaction among users, concurrent chat threads, and noise in the real world, and evaluates proactive agents on response timing, single-step response correctness, and multi-step response correctness. Experiments on eight LLMs and pipelines reveal that current agents frequently overact and struggle with event cancellation. Notably, even the state-of-the-art GPT-5.1 provides redundant assistance in 30% of cases and achieves only 26.7% recall in event cancellation scenarios. Further qualitative analysis reveals fundamental limitations of current LLMs as proactive agents, particularly in detecting implicit events and reasoning from the user’s first-person perspective.
BrowseComp-Verify: Benchmarking Self-derived Verification Agents in Web Search
Guanzhen Li | Shijie Li
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Guanzhen Li | Shijie Li
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Verification agents are increasingly used to judge candidate answers in web search, yet their own reliability remains underexplored. Existing verification methods often rely on annotated ground truths or manually crafted rubrics, limiting scalability under high annotation costs and the dynamic nature of the web. Hence, we propose the self-derived verification task, where an agent derives validation rules from a search query and verifies whether a candidate answer satisfies them using external tools, without human-provided rubrics or ground-truth answers. We further introduce BrowseComp-Verify, a benchmark of 3298 query-answer pairs constructed from 453 BrowseComp questions with reliable correctness labels. Using BrowseComp-Verify, we evaluate a broad suite of LLMs as self-derived verification agents. Most models complete the task with high coverage, but accurate judgment remains challenging. In particular, many models exhibit a conservative bias toward rejecting candidate answers: GPT-v5.2-Thinking-high achieves 99.04% accuracy on incorrect answers but only 20.39% on correct answers.
2024
MVP-Bench: Can Large Vision-Language Models Conduct Multi-level Visual Perception Like Humans?
Guanzhen Li | Yuxi Xie | Min-Yen Kan
Findings of the Association for Computational Linguistics: EMNLP 2024
Guanzhen Li | Yuxi Xie | Min-Yen Kan
Findings of the Association for Computational Linguistics: EMNLP 2024
Humans perform visual perception at multiple levels, including low-level object recognition and high-level semantic interpretation such as behavior understanding. Subtle differences in low-level details can lead to substantial changes in high-level perception. For example, substituting the shopping bag held by a person with a gun suggests violent behavior, implying criminal or violent activity. Despite significant advancements in various multimodal tasks, Large Visual Language Models (LVLMs) remain unexplored in their capabilities to conduct such multi-level visual perceptions.To investigate the perception gap between LVLMs and humans, we introduce MVP-Bench, the first visual–language benchmark systematically evaluating both low- and high-level visual perception of LVLMs. We construct MVP-Bench across natural and synthetic images to investigate how manipulated content influences model perception. Using MVP-Bench, we diagnose the visual perception of 10 open-source and 2 closed-source LVLMs, showing that high-level perception tasks significantly challenge existing LVLMs. The state-of-the-art GPT-4o only achieves an accuracy of 56% on Yes/No questions, compared with 74% in low-level scenarios. Furthermore, the performance gap between natural and manipulated images indicates that current LVLMs do not generalize in understanding the visual semantics of synthetic images as humans do.
V-DPO: Mitigating Hallucination in Large Vision Language Models via Vision-Guided Direct Preference Optimization
Yuxi Xie | Guanzhen Li | Xiao Xu | Min-Yen Kan
Findings of the Association for Computational Linguistics: EMNLP 2024
Yuxi Xie | Guanzhen Li | Xiao Xu | Min-Yen Kan
Findings of the Association for Computational Linguistics: EMNLP 2024
Large vision-language models (LVLMs) suffer from hallucination, resulting in misalignment between the output textual response and the input visual content. Recent research indicates that the over-reliance on the Large Language Model (LLM) backbone, as one cause of the LVLM hallucination, inherently introduces bias from language priors, leading to insufficient context attention to the visual inputs.We tackle this issue of hallucination by mitigating such over-reliance through preference learning. We propose Vision-guided Direct Preference Optimization (V-DPO) to enhance visual context learning at training time. To interpret the effectiveness and generalizability of V-DPO on different types of training data, we construct a synthetic dataset containing both response- and image-contrast preference pairs, compared against existing human-annotated hallucination samples. Our approach achieves significant improvements compared with baseline methods across various hallucination benchmarks. Our analysis indicates that V-DPO excels in learning from image-contrast preference data, demonstrating its superior ability to elicit and understand nuances of visual context. Our code is publicly available at https://github.com/YuxiXie/V-DPOhttps://github.com/YuxiXie/V-DPO.
2023
ECHo: A Visio-Linguistic Dataset for Event Causality Inference via Human-Centric Reasoning
Yuxi Xie | Guanzhen Li | Min-Yen Kan
Findings of the Association for Computational Linguistics: EMNLP 2023
Yuxi Xie | Guanzhen Li | Min-Yen Kan
Findings of the Association for Computational Linguistics: EMNLP 2023
We introduce ECHo (Event Causality Inference via Human-Centric Reasoning), a diagnostic dataset of event causality inference grounded in visio-linguistic social scenarios. ECHo employs real-world human-centric deductive information building on a television crime drama. ECHo requires the Theory-of-Mind (ToM) ability to understand and reason about social interactions based on multimodal information. Using ECHo, we propose a unified Chain-of-Thought (CoT) framework to assess the reasoning capability of current AI systems. Our ToM-enhanced CoT pipeline accommodates various large foundation models in both zero-shot and few-shot visio-linguistic reasoning. We use this framework to scrutinize recent large foundation models such as InstructGPT and MiniGPT-4 on three diagnostic human-centric tasks. Further analysis demonstrates ECHo as a challenging dataset to expose imperfections and inconsistencies in reasoning. Our data and code are publicly available at https://github.com/YuxiXie/ECHo.