Xiang Chen
Author directoryAlso published as: Xiang ‘Anthony’ Chen
Other people with similar names: Xiang ‘Anthony’ Chen, Xiang Chen, Xiang Chen
Unverified author pages with similar names: Xiang Chen
2026
SafeSteer: A Decoding-level Defense Mechanism for Multimodal Large Language Models
Xinyi Zeng | Xue Yang | Jingyuan Zhang | Huanqian Yan | Xiang Chen | Kaiwen Wei | Hankun Kang | Yu Tian
Findings of the Association for Computational Linguistics: ACL 2026
Xinyi Zeng | Xue Yang | Jingyuan Zhang | Huanqian Yan | Xiang Chen | Kaiwen Wei | Hankun Kang | Yu Tian
Findings of the Association for Computational Linguistics: ACL 2026
Multimodal large language models (MLLMs) are gaining increasing attention. Due to the heterogeneity of their input features, they face significant challenges in terms of jailbreak defenses. Current defense methods rely on costly fine-tuning or inefficient post-hoc interventions, limiting their ability to address novel attacks and involving performance trade-offs. To address the above issues, we explore the endogenous safety capabilities within MLLMs and quantify their intrinsic ability to discern harmfulness at both encoding and decoding stages. We observe that 1) MLLMs can distinguish the harmful and harmless inputs during decoding process, 2) Image-based attacks are more stealthy. Based on these insights, we introduce SafeSteer, a decoding-level defense mechanism for MLLMs. Specifically, it employs a lightweight discriminator, based on the MLLM’s own discriminative ability, to iteratively steer the decoding process toward safety. A safety alignment vector is also integrated to handle complex multimodal threats. Experiments on multiple MLLMs demonstrate that our proposed method can improve safety performance by up to 33.40% without fine-tuning.
DPN-LE: Dual Personality Neuron Localization and Editing for Large Language Models
Lifan Zheng | Xue Yang | Jiawei Chen | Chenyan WU | Jingyuan Zhang | Fanheng Kong | Xinyi Zeng | Xiang Chen | Yu Tian
Findings of the Association for Computational Linguistics: ACL 2026
Lifan Zheng | Xue Yang | Jiawei Chen | Chenyan WU | Jingyuan Zhang | Fanheng Kong | Xinyi Zeng | Xiang Chen | Yu Tian
Findings of the Association for Computational Linguistics: ACL 2026
With the widespread adoption of large language models (LLMs), understanding their personality representation mechanisms has become critical. As a novel paradigm in Personality Editing, most existing methods employ neuron-editing to locate and modify LLM neurons, requiring changes to numerous neurons and leading to significant performance degradation. This raises a fundamental question: Are all modified neurons directly related to personality representation? In this work, we investigate and quantify this specificity through assessments of general capability impact and representation-level patterns. We find that: 1) Current methods can change personalities but reduce overall performance. 2) Neurons are multifunctional, connecting personality traits and general knowledge. 3) Opposing personality traits demonstrate distinctly mutually exclusive representation patterns. Motivated by these findings, we propose DPN-LE (Dual Personality Neuron Localization and Editing), which identifies personality-specific neurons by contrasting MLP activations between high-trait and low-trait samples. DPN-LE constructs layer-wise steering vectors and applies dual-criterion filtering based on Cohen’s d effect size and activation magnitude to isolate mutually exclusive neuron subsets. Sparse linear intervention on these neurons enables precise personality control at inference time. Using only 1,000 contrastive sample pairs per trait, DPN-LE intervenes on ∼0.5% of neurons while achieving competitive personality control and substantially better capability preservation across reasoning tasks. Experiments on LLaMA-3-8B-Instruct and Qwen2.5-7B-Instruct demonstrate the effectiveness and generalizability of our approach.
DiffER: Diffusion Entity-Relation Modeling for Reversal Curse in Diffusion Large Language Models
Shaokai He | Kaiwen Wei | Xinyi Zeng | Xiang Chen | Xue Yang | Zhenyang Li | Jiang Zhong | Yu Tian
Findings of the Association for Computational Linguistics: ACL 2026
Shaokai He | Kaiwen Wei | Xinyi Zeng | Xiang Chen | Xue Yang | Zhenyang Li | Jiang Zhong | Yu Tian
Findings of the Association for Computational Linguistics: ACL 2026
The “reversal curse” refers to the phenomenon where large language models (LLMs) exhibit predominantly unidirectional behavior when processing logically bidirectional relationships. Prior work attributed this to autoregressive training—predicting the next token inherently favors left-to-right information flow over genuine bidirectional knowledge associations. However, we observe that Diffusion LLMs (DLLMs), despite being trained bidirectionally, also suffer from the reversal curse. To investigate the root causes, we conduct systematic experiments on DLLMs and identify three key reasons: 1) entity fragmentation during training, 2) data asymmetry, and 3) missing entity relations. Motivated by the analysis of these reasons, we propose Diffusion Entity-Relation Modeling (DiffER), which addresses the reversal curse through entity-aware training and balanced data construction. Specifically, DiffER introduces whole-entity masking, which mitigates entity fragmentation by predicting complete entities in a single step. DiffER further employs distribution-symmetric and relation-enhanced data construction strategies to alleviate data asymmetry and missing relations. Extensive experiments demonstrate that DiffER effectively alleviates the reversal curse in Diffusion LLMs, offering new perspectives for future research. The code is available at https://github.com/CQU-MM-Intelligent-Lab/DiffER.
Beyond Superficial Unlearning: Sharpness-Aware Robust Erasure of Hallucinations in Multimodal LLMs
Xianya Fang | Feiyang Ren | Xiang Chen | Yu Tian | Zhen Bi | Haiyang Yu | Sheng-Jun Huang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Xianya Fang | Feiyang Ren | Xiang Chen | Yu Tian | Zhen Bi | Haiyang Yu | Sheng-Jun Huang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Multimodal LLMs are powerful but prone to object hallucinations, which describe non-existent entities and harm reliability. While recent unlearning methods attempt to mitigate this, we identify a critical flaw: structural fragility. We empirically demonstrate that standard erasure achieves only superficial suppression, trapping the model in sharp minima where hallucinations catastrophically resurge after lightweight relearning. To ensure geometric stability, we propose Sharpness-Aware Robust Erasure (SARE), which casts unlearning as a targeted min-max optimization problem and leverages a targeted Sharpness-Aware Minimization (Targeted-SAM) mechanism to explicitly flatten the loss landscape around hallucinated concepts. By suppressing hallucinations under simulated worst-case parameter perturbations, our framework ensures robust removal stable against weight shifts. Extensive experiments demonstrate that SARE outperforms baselines in erasure efficacy while preserving general generation quality. Crucially, it maintains persistent hallucination suppression against relearning and parameter updates, validating the effectiveness of geometric stabilization.
Concise and Sufficient Sub-Sentence Citations for Retrieval-Augmented Generation
Guo Chen | Qiuyuan Li | Qiuxian Li | Hongliang Dai | Xiang Chen | Piji Li
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Guo Chen | Qiuyuan Li | Qiuxian Li | Hongliang Dai | Xiang Chen | Piji Li
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
In retrieval-augmented generation (RAG) question answering systems, generating citations for large language model (LLM) outputs enhances verifiability and helps users identify potential hallucinations. Existing citation generation methods for retrieval-augmented generation usually provide evidence at the paragraph or sentence level. Although such citations improve verifiability, they may still impose unnecessary reading burden on users: a cited sentence can contain irrelevant clauses, while an answer-bearing clause may lack sufficient contextual information such as the referred subject. In this paper, we study concise and sufficient sub-sentence citation generation, aiming to identify minimal yet self-contained evidence spans for answer verification. To this end, we first develop annotation guidelines for such citations and construct a corresponding dataset. To reduce annotation cost, we propose a data augmentation framework that generates synthetic citation annotations and filters low-quality instances using an evaluator model. Our experiments on the constructed dataset demonstrate that the proposed approach can generate high-quality and more readable citations. The code and data will be publicly released.
Beyond Dense States: Sparse Transcoders as Causally Testable Operators for LLM Latent Reasoning
Yadong Wang | Haodong Chen | Yu Tian | Chuanxing Geng | Dong Liang | Xiang Chen
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Yadong Wang | Haodong Chen | Yu Tian | Chuanxing Geng | Dong Liang | Xiang Chen
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Latent reasoning reduces the token-generation cost of chain-of-thought reasoning by replacing explicit intermediate tokens with continuous latent transitions. However, existing latent reasoning methods usually rely on dense and entangled transitions, making their reasoning trajectories difficult to inspect or intervene on. We introduce LSTR (Latent Sparse Transcoder Reasoning), a framework that turns sparse transcoders from post-hoc diagnostic tools into in-loop, intervenable transition components for latent reasoning. At each latent step, a Latent Transition Transcoder (LTT) combines a linear skip path with a Top-k sparse innovation path, exposing a small set of active sparse features. Under matched compression settings, LSTR offers a mechanistically inspectable alternative to dense latent reasoning. On GSM8K-Aug, ablating only a few top-active sparse features reduces accuracy by up to 16.5%, whereas analogous interventions have much smaller effects in dense latent baselines. These results indicate that the active sparse features are causally involved in the latent transition process, rather than merely post-hoc descriptors. Additional experiments on mathematical benchmarks and StrategyQA suggest that sparse latent transitions can preserve the compression benefits of latent reasoning while making the resulting trajectories more inspectable and intervenable.
2025
Graph-guided Cross-composition Feature Disentanglement for Compositional Zero-shot Learning
Yuxia Geng | Runkai Zhu | Jiaoyan Chen | Jintai Chen | Xiang Chen | Zhuo Chen | Shuofei Qiao | Yuxiang Wang | Xiaoliang Xu | Sheng-Jun Huang
Findings of the Association for Computational Linguistics: ACL 2025
Yuxia Geng | Runkai Zhu | Jiaoyan Chen | Jintai Chen | Xiang Chen | Zhuo Chen | Shuofei Qiao | Yuxiang Wang | Xiaoliang Xu | Sheng-Jun Huang
Findings of the Association for Computational Linguistics: ACL 2025
Disentanglement of visual features of primitives (i.e., attributes and objects) has shown exceptional results in Compositional Zero-shot Learning (CZSL). However, due to the feature divergence of an attribute (resp. object) when combined with different objects (resp. attributes), it is challenging to learn disentangled primitive features that are general across different compositions. To this end, we propose the solution of cross-composition feature disentanglement, which takes multiple primitive-sharing compositions as inputs and constrains the disentangled primitive features to be general across these compositions. More specifically, we leverage a compositional graph to define the overall primitive-sharing relationships between compositions, and build a task-specific architecture upon the recently successful large pre-trained vision-language model (VLM) CLIP, with dual cross-composition disentangling adapters (called L-Adapter and V-Adapter) inserted into CLIP’s frozen text and image encoders, respectively. Evaluation on three popular CZSL benchmarks shows that our proposed solution significantly improves the performance of CZSL, and its components have been verified by solid ablation studies. Our code and data are available at: https://github.com/zhurunkai/DCDA.
Agentic Knowledgeable Self-awareness
Shuofei Qiao | Zhisong Qiu | Baochang Ren | Xiaobin Wang | Xiangyuan Ru | Ningyu Zhang | Xiang Chen | Yong Jiang | Pengjun Xie | Fei Huang | Huajun Chen
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Shuofei Qiao | Zhisong Qiu | Baochang Ren | Xiaobin Wang | Xiangyuan Ru | Ningyu Zhang | Xiang Chen | Yong Jiang | Pengjun Xie | Fei Huang | Huajun Chen
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Large Language Models (LLMs) have achieved considerable performance across various agentic planning tasks. However, traditional approaches adopt a “flood irrigation” methodology that indiscriminately injects gold trajectories, external feedback, and domain knowledge into agent models. This practice overlooks the fundamental human cognitive principle of self-awareness - the ability to dynamically assess situational demands and strategically employ resources during decision-making. We propose Agentic Knowledgeable Self-awareness to address this gap, a novel paradigm enabling LLM-based agents to autonomously regulate knowledge utilization. Specifically, we propose KnowSelf, a data-centric approach that applies agents with knowledgeable self-awareness like humans. Concretely, we devise a heuristic situation judgement criterion to mark special tokens on the agent’s self-explored trajectories for collecting training data. Through a two-stage training process, the agent model can switch between different situations by generating specific special tokens, achieving optimal planning effects with minimal costs. Our experiments demonstrate that can outperform various strong baselines on different tasks and models with minimal use of external knowledge.
2024
Knowledge Mechanisms in Large Language Models: A Survey and Perspective
Mengru Wang | Yunzhi Yao | Ziwen Xu | Shuofei Qiao | Shumin Deng | Peng Wang | Xiang Chen | Jia-Chen Gu | Yong Jiang | Pengjun Xie | Fei Huang | Huajun Chen | Ningyu Zhang
Findings of the Association for Computational Linguistics: EMNLP 2024
Mengru Wang | Yunzhi Yao | Ziwen Xu | Shuofei Qiao | Shumin Deng | Peng Wang | Xiang Chen | Jia-Chen Gu | Yong Jiang | Pengjun Xie | Fei Huang | Huajun Chen | Ningyu Zhang
Findings of the Association for Computational Linguistics: EMNLP 2024
Understanding knowledge mechanisms in Large Language Models (LLMs) is crucial for advancing towards trustworthy AGI. This paper reviews knowledge mechanism analysis from a novel taxonomy including knowledge utilization and evolution. Knowledge utilization delves into the mechanism of memorization, comprehension and application, and creation. Knowledge evolution focuses on the dynamic progression of knowledge within individual and group LLMs. Moreover, we discuss what knowledge LLMs have learned, the reasons for the fragility of parametric knowledge, and the potential dark knowledge (hypothesis) that will be challenging to address. We hope this work can help understand knowledge in LLMs and provide insights for future research.
OneGen: Efficient One-Pass Unified Generation and Retrieval for LLMs
Jintian Zhang | Cheng Peng | Mengshu Sun | Xiang Chen | Lei Liang | Zhiqiang Zhang | Jun Zhou | Huajun Chen | Ningyu Zhang
Findings of the Association for Computational Linguistics: EMNLP 2024
Jintian Zhang | Cheng Peng | Mengshu Sun | Xiang Chen | Lei Liang | Zhiqiang Zhang | Jun Zhou | Huajun Chen | Ningyu Zhang
Findings of the Association for Computational Linguistics: EMNLP 2024
Despite the recent advancements in Large Language Models (LLMs), which have significantly enhanced the generative capabilities for various NLP tasks, LLMs still face limitations in directly handling retrieval tasks. However, many practical applications demand the seamless integration of both retrieval and generation. This paper introduces a novel and efficient One-pass Generation and retrieval framework (OneGen), designed to improve LLMs’ performance on tasks that require both generation and retrieval. The proposed framework bridges the traditionally separate training approaches for generation and retrieval by incorporating retrieval tokens generated autoregressively. This enables a single LLM to handle both tasks simultaneously in a unified forward pass. We conduct experiments on two distinct types of composite tasks, RAG and Entity Linking, to validate the pluggability, effectiveness, and efficiency of OneGen in training and inference. Furthermore, our results show that integrating generation and retrieval within the same context preserves the generative capabilities of LLMs while improving retrieval performance. To the best of our knowledge, OneGen is the first to enable LLMs to conduct vector retrieval during the generation.
2023
Reasoning with Language Model Prompting: A Survey
Shuofei Qiao | Yixin Ou | Ningyu Zhang | Xiang Chen | Yunzhi Yao | Shumin Deng | Chuanqi Tan | Fei Huang | Huajun Chen
Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Shuofei Qiao | Yixin Ou | Ningyu Zhang | Xiang Chen | Yunzhi Yao | Shumin Deng | Chuanqi Tan | Fei Huang | Huajun Chen
Proceedings of the 61st Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Reasoning, as an essential ability for complex problem-solving, can provide back-end support for various real-world applications, such as medical diagnosis, negotiation, etc. This paper provides a comprehensive survey of cutting-edge research on reasoning with language model prompting. We introduce research works with comparisons and summaries and provide systematic resources to help beginners. We also discuss the potential reasons for emerging such reasoning abilities and highlight future research directions. Resources are available at https://github.com/zjunlp/Prompt4ReasoningPapers (updated periodically).
2022
Good Visual Guidance Make A Better Extractor: Hierarchical Visual Prefix for Multimodal Entity and Relation Extraction
Xiang Chen | Ningyu Zhang | Lei Li | Yunzhi Yao | Shumin Deng | Chuanqi Tan | Fei Huang | Luo Si | Huajun Chen
Findings of the Association for Computational Linguistics: NAACL 2022
Xiang Chen | Ningyu Zhang | Lei Li | Yunzhi Yao | Shumin Deng | Chuanqi Tan | Fei Huang | Luo Si | Huajun Chen
Findings of the Association for Computational Linguistics: NAACL 2022
Multimodal named entity recognition and relation extraction (MNER and MRE) is a fundamental and crucial branch in information extraction. However, existing approaches for MNER and MRE usually suffer from error sensitivity when irrelevant object images incorporated in texts. To deal with these issues, we propose a novel Hierarchical Visual Prefix fusion NeTwork (HVPNeT) for visual-enhanced entity and relation extraction, aiming to achieve more effective and robust performance. Specifically, we regard visual representation as pluggable visual prefix to guide the textual representation for error insensitive forecasting decision. We further propose a dynamic gated aggregation strategy to achieve hierarchical multi-scaled visual features as visual prefix for fusion. Extensive experiments on three benchmark datasets demonstrate the effectiveness of our method, and achieve state-of-the-art performance.
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- Huajun Chen 5
- Yu Tian 5
- Ningyu Zhang 5
- Fei Huang 4
- Shuofei Qiao 4
- Shumin Deng 3
- Xue Yang 3
- Yunzhi Yao 3
- Xinyi Zeng 3
- Sheng-Jun Huang 2
- Yong Jiang 2
- Chuanqi Tan 2
- Kaiwen Wei 2
- Pengjun Xie 2
- Jingyuan Zhang 2
- Zhen Bi 1
- Guo Chen 1
- Haodong Chen 1
- Jiaoyan Chen 1
- Jiawei Chen 1
- Jintai Chen 1
- Zhuo Chen 1
- Hongliang Dai 1
- Xianya Fang 1
- Chuanxing Geng 1
- Yuxia Geng 1
- Jia-Chen Gu 1
- Shaokai He 1
- Hankun Kang 1
- Fanheng Kong 1
- Lei Li 1
- Piji Li (李丕绩) 1
- Qiuxian Li 1
- Qiuyuan Li 1
- Zhenyang Li 1
- Dong Liang 1
- Lei Liang 1
- Yixin Ou 1
- Cheng Peng 1
- Zhisong Qiu 1
- Baochang Ren 1
- Feiyang Ren 1
- Xiangyuan Ru 1
- Luo Si 1
- Mengshu Sun 1
- Chenyan WU 1
- Mengru Wang 1
- Peng Wang 1
- Xiaobin Wang 1
- Yadong Wang 1
- Yuxiang Wang 1
- Xiaoliang Xu 1
- Ziwen Xu 1
- Huanqian Yan 1
- Haiyang Yu 1
- Jintian Zhang 1
- Zhiqiang Zhang 1
- Lifan Zheng 1
- Jiang Zhong 1
- Jun Zhou 1
- Runkai Zhu 1