Peiyang Liu | 刘培阳 - PKU Ph.D. Student, RAG & LLM Researcher

Research研究方向

Retrieval-Augmented Generation 检索增强生成

Building robust and trustworthy RAG systems — from context compression and counterfactual debiasing to multimodal visual attribution and data theft detection. 构建鲁棒可信的 RAG 系统——涵盖上下文压缩、反事实去偏、多模态视觉归因以及数据盗用检测。

Context Compression Robust RAG Multimodal RAG RAG Security

LLM Reasoning & Post-Training 大模型推理与后训练

Improving how LLMs learn and reason after pretraining — synthesizing reasoning paths from search trajectories, diagnosing SFT failure modes, designing efficient reward models, and calibrating code generation. 提升大模型在预训练之后的学习与推理能力——从搜索轨迹合成推理路径、诊断 SFT 失效模式、设计高效奖励模型，到代码生成的层级校准。

Reasoning Reward Model SFT Analysis Code Generation Long Context

Information Retrieval & Text Embedding 信息检索与文本嵌入

Large-scale dense retrieval with embedding optimization — label enhancement & smoothing, knowledge distillation, data quality control, and cross-modal retrieval. 面向大规模稠密检索的嵌入优化——标签增强与平滑、知识蒸馏、数据质量控制以及跨模态检索。

Dense Retrieval Text Embedding Label Quality Knowledge Distillation Video Search

Publications发表论文

* denotes equal contribution · blue highlight denotes myself * 表示共同一作 · 蓝色高亮为本人

2026

Learning from Contrasts: Synthesizing Reasoning Paths from Diverse Search Trajectories

Peiyang Liu, Zhirui Chen, Xi Wang, Di Liang, Youru Li, Zhi Cai, Wei Ye

ACL 2026CCF-AOral The 64th Annual Meeting of the Association for Computational Linguistics

arXiv

NeuroSym-Cal: Bridging the Reasoning-Execution Gap in Code Generation via Hierarchical Calibration

Peiyang Liu, Yining Wang, Youru Li, Long Li, Zhi Cai, Wei Ye

ACL 2026Findings Findings of the Association for Computational Linguistics: ACL 2026

StructKV: Preserving the Structural Skeleton for Scalable Long-Context Inference

Zhirui Chen, Peiyang Liu, Ling Shao

ACL 2026Findings Findings of the Association for Computational Linguistics: ACL 2026

arXiv

Why Supervised Fine-Tuning Fails to Learn: A Systematic Study of Incomplete Learning in Large Language Models

Chao Xue, Yao Wang, Mengqiao Liu, Di Liang, Xingsheng Han, Peiyang Liu, Xianjie Wu, Chenyao Lu, Lei Jiang, Yu Lu, Haibo Shi, Shuang Liang, Minlong Peng, Flora D. Salim

ACL 2026CCF-A The 64th Annual Meeting of the Association for Computational Linguistics

arXiv

Reason Only When Needed: Efficient Generative Reward Modeling via Model-Internal Uncertainty

Chao Xue, Yao Wang, Mengqiao Liu, Di Liang, Xingsheng Han, Peiyang Liu, Xianjie Wu, Chenyao Lu, Lei Jiang, Yu Lu, Haibo Shi, Shuang Liang, Minlong Peng, Flora D. Salim

ACL 2026Findings Findings of the Association for Computational Linguistics: ACL 2026

arXiv

Parameter Importance is Not Static: Evolving Parameter Isolation for Supervised Fine-Tuning

Zekai Lin, Chao Xue, Di Liang, Xingsheng Han, Peiyang Liu, Xianjie Wu, Lei Jiang, Yu Lu, Bob Simons, Shuang Liang, Minlong Peng

ACL 2026CCF-AOral The 64th Annual Meeting of the Association for Computational Linguistics

arXiv

Chain of Evidence: Pixel-Level Visual Attribution for Iterative Retrieval-Augmented Generation

Peiyang Liu, Ziqiang Cui, Xi Wang, Di Liang, Wei Ye

SIGIR 2026CCF-AOral Proceedings of the 49th International ACM SIGIR Conference on Research and Development in Information Retrieval

arXiv

Beyond Semantic Relevance: Counterfactual Risk Minimization for Robust Retrieval-Augmented Generation

Peiyang Liu, Qiang Yan, Ziqiang Cui, Di Liang, Xi Wang, Wei Ye

SIGIR 2026CCF-AOral Proceedings of the 49th International ACM SIGIR Conference on Research and Development in Information Retrieval

arXiv

ToolSafe: Enhancing Tool Invocation Safety of LLM-based Agents via Proactive Step-level Guardrail and Feedback

Yutao Mou, Zhangchi Xue, Lijun Li, Peiyang Liu, Shikun Zhang, Wei Ye, Jing Shao

ACL 2026Findings Findings of the Association for Computational Linguistics: ACL 2026

arXiv

SQL-ASTRA: Alleviating Sparse Feedback in Agentic SQL via Column-Set Matching and Trajectory Aggregation

Long Li, Zhijian Zhou, Jiangxuan Long, Peiyang Liu, Weidi Xu, Zhe Wang, Shirui Pan, Chao Qu

ACL 2026Findings Findings of the Association for Computational Linguistics: ACL 2026

arXiv

Less Is More: Elevating RAG via Performance-Driven Context Compression

Ziqiang Cui, Yunpeng Weng, Xing Tang, Peiyang Liu, Shiwei Li, Bowei He, Jiamin Chen, Yansen Zhang, Xiuqiang He, Rui Zhang, Chen Ma

ICML 2026CCF-A The 43rd International Conference on Machine Learning

2025

Queries Are Not Alone: Clustering Text Embeddings for Video Search

Peiyang Liu, Xi Wang, Ziqiang Cui, Wei Ye

SIGIR 2025CCF-AOral Proceedings of the 48th International ACM SIGIR Conference on Research and Development in Information Retrieval, pp. 874-883

arXiv

Who Stole Your Data? A Method for Detecting Unauthorized RAG Theft

Peiyang Liu, Ziqiang Cui, Di Liang, Wei Ye

Preprint arXiv:2510.07728, 2025

arXiv

Structural Reward Model: Enhancing Interpretability, Efficiency, and Scalability in Reward Modeling

Xiaoyu Liu, Di Liang, Hongyu Shan, Peiyang Liu, Yonghao Liu, Muling Wu, Yuntao Li, Xianjie Wu, Li Miao, Jiangrong Shen, et al.

EMNLP 2025CCF-B Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing: Industry Track, pp. 672-685

Paper

Semantic Retrieval Augmented Contrastive Learning for Sequential Recommendation

Ziqiang Cui, Yunpeng Weng, Xing Tang, Xiaokun Zhang, Shiwei Li, Peiyang Liu, Bowei He, Dugang Liu, Weihong Luo, Xiuqiang He, et al.

NeurIPS 2025CCF-A The 39th Annual Conference on Neural Information Processing Systems

arXiv

CORE-RAG: Lossless Compression for Retrieval-Augmented LLMs via Reinforcement Learning

Ziqiang Cui, Yunpeng Weng, Xing Tang, Peiyang Liu, Shiwei Li, Bowei He, Jiamin Chen, Yansen Zhang, Xiuqiang He, Chen Ma

Preprint arXiv:2508.19282, 2025

arXiv

2024

Unsupervised Corrupt Data Detection for Text Training

Peiyang Liu

ESWA 2024CCF-C Expert Systems with Applications, Volume 248, 123335

Paper

2023

Retrieval-Based Unsupervised Noisy Label Detection on Text Data

Peiyang Liu, Jinyu Yang, Lin Wang, Sen Wang, Yunlai Hao, Huihui Bai

CIKM 2023CCF-B Proceedings of the 32nd ACM International Conference on Information and Knowledge Management, pp. 4099-4104

Paper

2022

Label Smoothing for Text Mining

Peiyang Liu, Xiangyu Xi, Wei Ye, Shikun Zhang

COLING 2022CCF-B Proceedings of the 29th International Conference on Computational Linguistics, pp. 2210-2219

Paper

2021

Improving Embedding-based Large-scale Retrieval via Label Enhancement

Peiyang Liu, Xi Wang, Sen Wang, Wei Ye, Xiangyu Xi, Shikun Zhang

EMNLP 2021Findings Findings of the Association for Computational Linguistics: EMNLP 2021, pp. 133-142

Paper

Distilling Knowledge from BERT into Simple Fully Connected Neural Networks for Efficient Vertical Retrieval

Peiyang Liu, Xi Wang, Lin Wang, Wei Ye, Xiangyu Xi, Shikun Zhang

CIKM 2021CCF-B Proceedings of the 30th ACM International Conference on Information & Knowledge Management, pp. 3965-3975

Paper

QuadrupletBERT: An Efficient Model For Embedding-Based Large-Scale Retrieval

Peiyang Liu, Sen Wang, Xi Wang, Wei Ye, Shikun Zhang

NAACL 2021CCF-B Proceedings of the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies, pp. 3734-3739

Paper

2020

Not All Synonyms Are Created Equal: Incorporating Similarity of Synonyms to Enhance Word Embeddings

Peiyang Liu, Wei Ye, Xiangyu Xi, Tong Wang, Jinglei Zhang, Shikun Zhang

IJCNN 2020CCF-C 2020 International Joint Conference on Neural Networks, pp. 1-8, IEEE

Paper