Junfeng Fang
Author directory2026
Self-Evaluation Is Already There: Eliciting Latent Judge Calibration in Base LLMs with Minimal Data
XiuYu Zhang | Yi Shan | Junfeng Fang | Zhenkai Liang
Findings of the Association for Computational Linguistics: EMNLP 2026
XiuYu Zhang | Yi Shan | Junfeng Fang | Zhenkai Liang
Findings of the Association for Computational Linguistics: EMNLP 2026
Large language models are increasingly evaluated by other models, raising a natural question: can a model predict how a judge will score its own output? We find that the ability is largely present before any targeted training: prompted few-shot, a base model already predicts an external judge’s multi-attribute quality scores on open-ended responses well above chance across three benchmarks. We introduce Self-Evaluation Elicitation (SEE), a method that surfaces this latent ability through a short cycle comprising a calibration-coupled reinforcement learning phase that improves the answer and predicts the judge, followed by a masked distillation phase that sharpens the prediction while leaving the answer untouched. From 160 unique examples, roughly 31× fewer than a reinforcement learning baseline, SEE improves held-out calibration across three benchmarks while preserving answer quality. The elicited self-evaluation is sharply localized within the model’s own token distribution and stable across judges it was never trained against, indicating a transferable notion of quality rather than a single judge’s preference. These results reframe judge-aligned self-evaluation as a problem of elicitation rather than acquisition.
ResMerge: Residual-based Spectral Merging of Large Language Models
Yandu Sun | ZhiYan Hou | Hongyan An | Weizhen Wang | Haokai Ma | Yuheng Jia | Junfeng Fang | Haiyun Guo | Jinqiao Wang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Yandu Sun | ZhiYan Hou | Hongyan An | Weizhen Wang | Haokai Ma | Yuheng Jia | Junfeng Fang | Haiyun Guo | Jinqiao Wang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Model merging offers a training-free way to combine multiple post-trained expert models, but merging experts obtained through reinforcement learning (RL) remains challenging. Existing spectral merging methods often assume that leading singular directions contain the main task signal, while lower-energy residual components can be compressed, selected, or attenuated to reduce interference. We find that this assumption does not hold for RL task vectors: after decomposing each task vector into a leading spectral head and a residual component, both parts can independently recover substantial behavior knowledge, while exhibiting different merging properties. The head is highly concentrated and informative but more prone to sharp cross-expert conflicts, whereas the residual component is more dispersed and provides a more stable basis for aggregation. Based on this observation, we propose ResMerge, a residual-based spectral merging framework for RL experts. ResMerge first constructs a stable residual backbone with Spherical Residual Consensus Adaptation, which estimates a reliability-weighted consensus direction on the Frobenius sphere. It then reintroduces leading-head information through a Lightweight Head Correction module gated by positive cross-expert agreement. Experiments across multiple RL expert groups and capability domains show that ResMerge better preserves expert capabilities than representative task-vector and spectral merging baselines.
Unified Context Evolution for LLM Agents
Zixuan Zhu | Yitong Hu | Yong Dai | Junfeng Fang | Chunyang Jiang | Senkang Hu | Yuzhi Zhao
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Zixuan Zhu | Yitong Hu | Yong Dai | Junfeng Fang | Chunyang Jiang | Senkang Hu | Yuzhi Zhao
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
LLM-based agents can solve multi-step interactive tasks by combining reasoning with environment feedback, yet each episode starts from the same fixed context and any useful strategy discovered along the way is lost once the task ends. Existing approaches either limit learning to the current task or pool all experience into a single untyped store, without distinguishing knowledge types, tracking quality through use, or balancing what the library still lacks. We introduce Unified Context Evolution (UCE), a gradient-free framework that externalizes agent experience into an evolving library of typed Evolvable Context Units (ECUs). UCE decomposes experience into four complementary types (Memory, Strategy, Workflow, and Skill), each generated from trajectories under type-specific conditions, retrieved at decision time, scored through repeated usage outcomes, and pruned when no longer valuable. A scheduling module allocates each cycle’s generation budget toward the types where the library is weakest. Across two interactive benchmarks, UCE raises ALFWorld success from 75.4% to 96.3% and WebShop task score from 45.1% to 61.3%, and remains effective across alternative actor reasoning backbones without model retraining.
On-Policy Distillation with Curriculum Turn-level Guidance for Multi-turn Agents
Gengsheng Li | Mao Zheng | Mingyang Song | Ruiqi Liu | Tianyu Yang | Jie Sun | Qiyong Zhong | Dan Zhang | Haiyun Guo | Junfeng Fang | Jinqiao Wang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Gengsheng Li | Mao Zheng | Mingyang Song | Ruiqi Liu | Tianyu Yang | Jie Sun | Qiyong Zhong | Dan Zhang | Haiyun Guo | Junfeng Fang | Jinqiao Wang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Multi-turn agents that plan, invoke tools, and interact with environments offer a promising paradigm for solving complex tasks, yet their capabilities typically rely on very large models whose inference cost is prohibitive in practice. On-Policy Distillation (OPD) is a natural recipe for transferring such capabilities to smaller students, but we find that it suffers a characteristic failure mode in this setting: small student errors compound across turns and push the trajectory out of the teacher’s familiar state distribution, so the teacher’s supervision becomes least reliable precisely where the student needs it most. We propose Guided On-Policy Distillation (Guided-OPD), a simple yet effective algorithm that mixes teacher- and student-generated turns within each rollout and schedules the teacher’s intervention probability along a curriculum that decays to zero. Strong guidance keeps early trajectories close to the teacher distribution and is then gradually withdrawn to recover the purely on-policy regime used at inference. On ALFWorld, ScienceWorld, and WebShop, distilling Qwen3 students from a Qwen3-30B-A3B teacher, Guided-OPD yields average relative gains of 21.1% in Score and 25.5% in Success Rate over vanilla OPD, with larger gains on smaller students.
Mitigating Hallucinations in Large Vision-Language Models without Performance Degradation
Xingyu Zhu | Junfeng Fang | Shuo Wang | Beier Zhu | Zhicai Wang | Yonghui Yang | Xiangnan He
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Xingyu Zhu | Junfeng Fang | Shuo Wang | Beier Zhu | Zhicai Wang | Yonghui Yang | Xiangnan He
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Large Vision-Language Models (LVLMs) exhibit powerful generative capabilities but frequently produce hallucinations that compromise output reliability. Fine tuning on annotated data devoid of hallucinations offers the most direct solution, while its high computational cost motivates recent representation-based methods, which focus on mitigating hallucinatory components within hidden representations. Though efficient, we empirically observe that these methods degrade general generation capacity due to incomplete extraction of hallucination components and non-selective parameter updates. To address these limitations, we propose MPD, a dual-stage framework for mitigating hallucinations without performance degradation. Specifically, our MPD relies on two essential factors: (1) semantic-aware component disentanglement to extract pure hallucination components, and (2) interpretable parameter updates that selectively modify parameters most relevant to hallucination. Extensive experiments demonstrate that MPD achieves state-of-the-art performance, reducing hallucinations by 23.4% while maintaining 97.4% of general generative capability as evaluated on LLaVA-Bench and MME, with no additional computational cost.
2025
Steering LVLMs via Sparse Autoencoder for Hallucination Mitigation
Zhenglin Hua | Jinghan He | Zijun Yao | Tianxu Han | Haiyun Guo | Yuheng Jia | Junfeng Fang
Findings of the Association for Computational Linguistics: EMNLP 2025
Zhenglin Hua | Jinghan He | Zijun Yao | Tianxu Han | Haiyun Guo | Yuheng Jia | Junfeng Fang
Findings of the Association for Computational Linguistics: EMNLP 2025
Large vision-language models (LVLMs) have achieved remarkable performance on multimodal tasks. However, they still suffer from hallucinations, generating text inconsistent with visual input, posing significant risks in real-world applications. Existing approaches to address this issue focus on incorporating external knowledge bases, alignment training, or decoding strategies, all of which require substantial computational cost and time. Recent works try to explore more efficient alternatives by adjusting LVLMs’ internal representations. Although promising, these methods may cause hallucinations to be insufficiently suppressed or lead to excessive interventions that negatively affect normal semantics. In this work, we leverage sparse autoencoders (SAEs) to identify semantic directions closely associated with faithfulness or hallucination, extracting more precise and disentangled hallucination-related representations. Our analysis demonstrates that interventions along the identified faithful direction can mitigate hallucinations, while those along the hallucinatory direction can exacerbate them. Building on these insights, we propose Steering LVLMs via SAE Latent Directions (SSL), a plug-and-play method based on SAE-derived latent directions to mitigate hallucinations in LVLMs. Extensive experiments demonstrate that SSL significantly outperforms existing decoding approaches in mitigating hallucinations, while maintaining transferability across different model architectures with negligible additional time overhead. The code is available at https://github.com/huazhenglin2003/SSL.
Knowledge Graph-Driven Memory Editing with Directional Interventions
Jinhu Fu | Kun Wang | Chongye Guo | Junfeng Fang | Wentao Zhang | Sen Su
Findings of the Association for Computational Linguistics: EMNLP 2025
Jinhu Fu | Kun Wang | Chongye Guo | Junfeng Fang | Wentao Zhang | Sen Su
Findings of the Association for Computational Linguistics: EMNLP 2025
Large Language Models (LLMs) have revolutionized language processing and understanding, yet their performance is hampered by inaccuracies and outdated information. Model editing techniques offer a solution but face two key challenges: (I) Most methods inject knowledge by constructing rigid loss, which leads to poor compatibility when dealing with higher-order multi-hop problems. (II) Locate-then-edit vein, by altering pre-trained parameters, inevitably affect normal knowledge and even face the catastrophic forgetting. In this paper, we introduce KGMET, a framework that constructs knowledge graphs using available information to guide the direction of knowledge editing, enabling consistent, aligned, and stable information during large-scale editing scenario. Furthermore, KGMET goes beyond this by employing orthogonal constraints to block the interference of irrelevant information, ensuring the updates are both controllable and generalizable. Experiments on Multi-Conterfact, ZsRE, and MQuAKE datasets using Llama-3-8B, GPT-J-6B, and GPT-2-XL models showcase improvements over state-of-the-art methods, with ↑ 5%-17% in multi-hop tasks while remaining generalizable (at least ↑ 20% in fluency). Our code is available on Github.
Safety in Large Reasoning Models: A Survey
Cheng Wang | Yue Liu | Baolong Bi | Duzhen Zhang | Zhong-Zhi Li | Yingwei Ma | Yufei He | Shengju Yu | Xinfeng Li | Junfeng Fang | Jiaheng Zhang | Bryan Hooi
Findings of the Association for Computational Linguistics: EMNLP 2025
Cheng Wang | Yue Liu | Baolong Bi | Duzhen Zhang | Zhong-Zhi Li | Yingwei Ma | Yufei He | Shengju Yu | Xinfeng Li | Junfeng Fang | Jiaheng Zhang | Bryan Hooi
Findings of the Association for Computational Linguistics: EMNLP 2025
Large Reasoning Models (LRMs) have exhibited extraordinary prowess in tasks like mathematics and coding, leveraging their advanced reasoning capabilities. Nevertheless, as these capabilities progress, significant concerns regarding their vulnerabilities and safety have arisen, which can pose challenges to their deployment and application in real-world settings. This paper presents the first comprehensive survey of LRMs, meticulously exploring and summarizing the newly emerged safety risks, attacks, and defense strategies specific to these powerful reasoning-enhanced models. By organizing these elements into a detailed taxonomy, this work aims to offer a clear and structured understanding of the current safety landscape of LRMs, facilitating future research and development to enhance the security and reliability of these powerful models.
Forget the Token and Pixel: Rethinking Gradient Ascent for Concept Unlearning in Multimodal Generative Models
Jiaqi Li | Chuanyi Zhang | Miaozeng Du | Hui Zhang | Yongrui Chen | Qianshan Wei | Junfeng Fang | Ruipeng Wang | Sheng Bi | Guilin Qi
Findings of the Association for Computational Linguistics: ACL 2025
Jiaqi Li | Chuanyi Zhang | Miaozeng Du | Hui Zhang | Yongrui Chen | Qianshan Wei | Junfeng Fang | Ruipeng Wang | Sheng Bi | Guilin Qi
Findings of the Association for Computational Linguistics: ACL 2025
Gradient Ascent (GA) has emerged as a promising approach for concept unlearning in Multimodal Generative Models (MGMs), such as Multimodal Large Language Models (MLLMs) and Stable Diffusion Models (SDMs). Despite its effectiveness in removing undesired knowledge, GA leads to severe utility degradation in MGMs. In this paper, we explore the mechanism behind this degradation by quantifying two distinct forms of knowledge in MGMs: (i) Conceptual Knowledge, which represents specific information about concepts; (ii) Natural Knowledge, which refers to the ability to produce coherent and logically structured outputs. Our analysis reveals that applying GA globally not only removes the targeted Conceptual Knowledge but also inadvertently diminishes Natural Knowledge, resulting in utility collapse. To address this issue, we propose Forget the Token and Pixel (FTTP), a novel approach that selectively applies GA to targeted Conceptual Knowledge while preserving Natural Knowledge through Gradient Descent (GD). FTTP eliminates the need for additional retain sets and a large number of training steps, thereby reducing computational resource costs. Extensive experiments demonstrate FTTP’s efficiency and superior utility-unlearning tradeoff for both text and image generation tasks. Our source code will be released in the near future.
Context-DPO: Aligning Language Models for Context-Faithfulness
Baolong Bi | Shaohan Huang | Yiwei Wang | Tianchi Yang | Zihan Zhang | Haizhen Huang | Lingrui Mei | Junfeng Fang | Zehao Li | Furu Wei | Weiwei Deng | Feng Sun | Qi Zhang | Shenghua Liu
Findings of the Association for Computational Linguistics: ACL 2025
Baolong Bi | Shaohan Huang | Yiwei Wang | Tianchi Yang | Zihan Zhang | Haizhen Huang | Lingrui Mei | Junfeng Fang | Zehao Li | Furu Wei | Weiwei Deng | Feng Sun | Qi Zhang | Shenghua Liu
Findings of the Association for Computational Linguistics: ACL 2025
Reliable responses from large language models (LLMs) require adherence to user instructions and retrieved information. While alignment techniques help LLMs align with human intentions and values, improving context-faithfulness through alignment remains underexplored. To address this, we propose Context-DPO, the first alignment method specifically designed to enhance LLMs’ context-faithfulness. We introduce ConFiQA, a benchmark that simulates Retrieval-Augmented Generation (RAG) scenarios with knowledge conflicts to evaluate context-faithfulness. By leveraging faithful and stubborn responses to questions with provided context from ConFiQA, our Context-DPO aligns LLMs through direct preference optimization. Extensive experiments demonstrate that our Context-DPO significantly improves context-faithfulness, achieving 35% to 280% improvements on popular open-source models. Further analysis demonstrates that Context-DPO preserves LLMs’ generative capabilities while providing interpretable insights into context utilization.
Decoding by Contrasting Knowledge: Enhancing Large Language Model Confidence on Edited Facts
Baolong Bi | Shenghua Liu | Lingrui Mei | Yiwei Wang | Junfeng Fang | Pengliang Ji | Xueqi Cheng
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Baolong Bi | Shenghua Liu | Lingrui Mei | Yiwei Wang | Junfeng Fang | Pengliang Ji | Xueqi Cheng
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
The knowledge within large language models (LLMs) may become outdated quickly. While in-context editing (ICE) is currently the most effective method for knowledge editing (KE), it is constrained by the black-box modeling of LLMs and thus lacks interpretability. Our work aims to elucidate the superior performance of ICE in KE by analyzing the impacts of in-context new knowledge on token-wise distributions. We observe that despite a significant boost in logits of the new knowledge, the performance of ICE is still hindered by stubborn knowledge. We propose a novel approach termed Decoding by Contrasting Knowledge (DeCK). DeCK derives the distribution of the next token by contrasting the logits obtained from the newly edited knowledge guided by ICE with those from the unedited parametric knowledge. Our experiments demonstrate that DeCK enhances the confidence of LLMs in edited facts. For instance, it improves the performance of LLaMA3-8B-instruct on MQuAKE by up to 219%, demonstrating its capability to strengthen ICE. DeCK can be easily integrated into any ICE method as a decoding component to enhance editing capabilities.
Neuron-Level Sequential Editing for Large Language Models
Houcheng Jiang | Junfeng Fang | Tianyu Zhang | Baolong Bi | An Zhang | Ruipeng Wang | Tao Liang | Xiang Wang
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Houcheng Jiang | Junfeng Fang | Tianyu Zhang | Baolong Bi | An Zhang | Ruipeng Wang | Tao Liang | Xiang Wang
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
This work explores sequential model editing in large language models (LLMs), a critical task that involves modifying internal knowledge within LLMs continuously through multi-round editing, each incorporating updates or corrections to adjust the model’s outputs without the need for costly retraining. Existing model editing methods, especially those that alter model parameters, typically focus on single-round editing and often face significant challenges in sequential model editing-most notably issues of model forgetting and failure. To address these challenges, we introduce a new model editing method, namely Neuron-level Sequential Editing (NSE), tailored for supporting sequential model editing. Specifically, we optimize the target layer’s hidden states using the model’s original weights to prevent model failure. Furthermore, we iteratively select neurons in multiple layers for editing based on their activation values to mitigate model forgetting. Our empirical experiments demonstrate that NSE significantly outperforms current modifying parameters model editing methods, marking a substantial advancement in the field of sequential model editing. Our code is released on https://anonymous.4open.science/r/NSE-0A8D/.
Cracking the Code of Hallucination in LVLMs with Vision-aware Head Divergence
Jinghan He | Kuan Zhu | Haiyun Guo | Junfeng Fang | Zhenglin Hua | Yuheng Jia | Ming Tang | Tat-Seng Chua | Jinqiao Wang
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Jinghan He | Kuan Zhu | Haiyun Guo | Junfeng Fang | Zhenglin Hua | Yuheng Jia | Ming Tang | Tat-Seng Chua | Jinqiao Wang
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Large vision-language models (LVLMs) have made substantial progress in integrating large language models (LLMs) with visual inputs, enabling advanced multimodal reasoning. Despite their success, a persistent challenge is hallucination—where generated text fails to accurately reflect visual content—undermining both accuracy and reliability. Existing methods focus on alignment training or decoding refinements but primarily address symptoms at the generation stage without probing the underlying causes. In this work, we investigate the internal mechanisms driving hallucination in LVLMs, with an emphasis on the multi-head attention module. Specifically, we introduce Vision-aware Head Divergence (VHD), a metric that quantifies the sensitivity of attention head outputs to visual context. Based on this, our findings reveal the presence of vision-aware attention heads that are more attuned to visual information; however, the model’s overreliance on its prior language patterns is closely related to hallucinations. Building on these insights, we propose Vision-aware Head Reinforcement (VHR), a training-free approach to mitigate hallucination by enhancing the role of vision-aware attention heads. Extensive experiments demonstrate that our method achieves superior performance compared to state-of-the-art approaches in mitigating hallucinations, while maintaining high efficiency with negligible additional time overhead. The code is available at https://github.com/jinghan1he/VHR.
2024
MolTC: Towards Molecular Relational Modeling In Language Models
Junfeng Fang | Shuai Zhang | Chang Wu | Zhengyi Yang | Zhiyuan Liu | Sihang Li | Kun Wang | Wenjie Du | Xiang Wang
Findings of the Association for Computational Linguistics: ACL 2024
Junfeng Fang | Shuai Zhang | Chang Wu | Zhengyi Yang | Zhiyuan Liu | Sihang Li | Kun Wang | Wenjie Du | Xiang Wang
Findings of the Association for Computational Linguistics: ACL 2024
Molecular Relational Learning (MRL), aiming to understand interactions between molecular pairs, plays a pivotal role in advancing biochemical research. Recently, the adoption of large language models (LLMs), known for their vast knowledge repositories and advanced logical inference capabilities, has emerged as a promising way for efficient and effective MRL. Despite their potential, these methods predominantly rely on textual data, thus not fully harnessing the wealth of structural information inherent in molecular graphs. Moreover, the absence of a unified framework exacerbates the issue of insufficient data exploitation, as it hinders the sharing of interaction mechanism learned across various datasets. To address these challenges, this work proposes a novel LLM-based multi-modal framework for molecular interaction modeling following Chain-of-Thought (CoT) theory, termed MolTC, which effectively integrate graphical information of two molecules in pair. To train this integrated framework efficiently, we introduce a multi-hierarchical CoT theory to refine its training paradigm, and conduct a comprehensive Molecular Interactive Instructions dataset for the development of biochemical LLMs involving MRL.Our experiments,conducted across various datasets involving over 4,000,000 molecular pairs, exhibit the superiority of our method over current GNN and LLM-based baselines. Code is available at https://github.com/MangoKiller/MolTC.
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- Baolong Bi 4
- Haiyun Guo 4
- Yuheng Jia 3
- Jinqiao Wang 3
- Jinghan He 2
- Zhenglin Hua 2
- Shenghua Liu 2
- Lingrui Mei 2
- Kun Wang 2
- Ruipeng Wang 2
- Xiang Wang 2
- Yiwei Wang 2
- Hongyan An 1
- Sheng Bi 1
- Yongrui Chen 1
- Xueqi Cheng (程学旗) 1
- Tat-Seng Chua 1
- Yong Dai 1
- Weiwei Deng 1
- Miaozeng Du 1
- Wenjie Du 1
- Jinhu Fu 1
- Chongye Guo 1
- Tianxu Han 1
- Xiangnan He 1
- Yufei He 1
- Bryan Hooi 1
- ZhiYan Hou 1
- Senkang Hu 1
- Yitong Hu 1
- Haizhen Huang 1
- Shaohan Huang 1
- Pengliang Ji 1
- Chunyang Jiang 1
- Houcheng Jiang 1
- Gengsheng Li 1
- Jiaqi Li 1
- Sihang Li 1
- Xinfeng Li 1
- Zehao Li 1
- Zhong-Zhi Li 1
- Tao Liang 1
- Zhenkai Liang 1
- Ruiqi Liu 1
- Yue Liu 1
- Zhiyuan Liu 1
- Yingwei MA 1
- Haokai Ma 1
- Guilin Qi 1
- Yi Shan 1
- Mingyang Song 1
- Sen Su 1
- Feng Sun 1
- Jie Sun 1
- Yandu Sun 1
- Ming Tang 1
- Cheng Wang 1
- Shuo Wang 1
- Weizhen Wang 1
- Zhicai Wang 1
- Furu Wei 1
- Qianshan Wei 1
- Chang Wu 1
- Tianchi Yang 1
- Tianyu Yang 1
- Yonghui Yang 1
- Zhengyi Yang 1
- Zijun Yao 1
- Shengju Yu 1
- An Zhang 1
- Chuanyi Zhang 1
- Dan Zhang 1
- Duzhen Zhang 1
- Hui Zhang 1
- Jiaheng Zhang 1
- Qi Zhang 1
- Shuai Zhang 1
- Tianyu Zhang 1
- Wentao Zhang 1
- XiuYu Zhang 1
- Zihan Zhang 1
- Yuzhi Zhao 1
- Mao Zheng 1
- Qiyong Zhong 1
- Beier Zhu 1
- Kuan Zhu 1
- Xingyu Zhu 1
- Zixuan Zhu 1