Yifan Zhou
Author directory2026
Synapse: Empowering LLM Agents with Episodic-Semantic Memory via Spreading Activation
Hanqi Jiang | Junhao Chen | Yi Pan | Ling Chen | Weihang You | Yifan Zhou | Ruidong Zhang | Yohannes Abate | Tianming Liu
Findings of the Association for Computational Linguistics: ACL 2026
Hanqi Jiang | Junhao Chen | Yi Pan | Ling Chen | Weihang You | Yifan Zhou | Ruidong Zhang | Yohannes Abate | Tianming Liu
Findings of the Association for Computational Linguistics: ACL 2026
While Large Language Models (LLMs) excel at generalized reasoning, standard retrieval-augmented approaches fail to address the disconnected nature of long-term agentic memory. To bridge this gap, we introduce Synapse (Synergistic Associative Processing Semantic Encoding), a unified memory architecture that transcends static vector similarity. Drawing from cognitive science, Synapse models memory as a dynamic graph where relevance emerges from spreading activation rather than pre-computed links. By integrating lateral inhibition and temporal decay, the system dynamically highlights relevant sub-graphs while filtering interference. We implement a Triple Hybrid Retrieval strategy that fuses geometric embeddings with activation-based graph traversal. Extensive evaluations on the LoCoMo benchmark show that Synapse significantly outperforms state-of-the-art methods in complex temporal and multi-hop reasoning tasks, offering a robust solution to the “Contextual Tunneling” problem.
SCOPE: Stepwise Calibration of Reasoning Confidence with Outcome-Grounded Prefix Evidence
Huaqin Zhao | Yifan Zhou | Bolun Sun | Chao Cao | Yiwei Li | Zhaojun Ding | Lu Zhang | Tianming Liu | Jin Lu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Huaqin Zhao | Yifan Zhou | Bolun Sun | Chao Cao | Yiwei Li | Zhaojun Ding | Lu Zhang | Tianming Liu | Jin Lu
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Reinforcement learning with verifiable rewards (RLVR) improves language-model reasoning using outcome-level supervision, but this supervision is temporally coarse: it indicates whether a trajectory ends with a correct answer, without revealing when the reasoning becomes reliable or silently fails. Existing verbalized-confidence methods typically calibrate a single confidence score after the final answer, leaving intermediate uncertainty unobserved. We propose SCOPE (Stepwise Calibration with Outcome-grounded Prefix Evidence), which trains reasoning models to emit confidence after each reasoning step. SCOPE interprets step confidence as the model’s prefix-conditioned belief in the gold answer: how likely the gold answer is under the reasoning prefix generated so far. During training, SCOPE constructs a soft target by scoring the gold answer conditioned on each reasoning prefix under the current policy. It then distills this signal with a two-stage masked RL objective: the first stage stabilizes the output format and final-answer accuracy, while the second stage performs calibration-only masked updates by applying stepwise and final-confidence rewards only to the numerical tokens inside the emitted confidence spans. Experiments on mathematical reasoning benchmarks show that SCOPE improves stepwise and final-confidence calibration while preserving final-answer reasoning performance. We further show that the resulting confidence signals support downstream inference-time control, enabling more reliable Learn-Then-Test risk control and stronger confidence-weighted aggregation.
Scaling Behaviors of LLM Reinforcement Learning Post-Training: An Empirical Study in Mathematical Reasoning
Zelin Tan | Hejia Geng | Xiaohang Yu | Mulei Zhang | Guancheng Wan | Yifan Zhou | Qiang He | Xiangyuan Xue | Heng Zhou | Yutao Fan | Zhong-Zhi Li | Zaibin Zhang | Guibin Zhang | Chen Zhang | Zhenfei Yin | Philip Torr | Lei Bai
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Zelin Tan | Hejia Geng | Xiaohang Yu | Mulei Zhang | Guancheng Wan | Yifan Zhou | Qiang He | Xiangyuan Xue | Heng Zhou | Yutao Fan | Zhong-Zhi Li | Zaibin Zhang | Guibin Zhang | Chen Zhang | Zhenfei Yin | Philip Torr | Lei Bai
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
While scaling laws for large language models (LLMs) during pre-training have been extensively studied, their behavior under reinforcement learning (RL) post-training remains largely unexplored. This paper investigates the scaling behavior of Large Language Model (LLM) reinforcement learning post-training, focusing on mathematical reasoning. Through experiments across the Qwen2.5 series (0.5B to 72B), we characterize how model scale, data, and compute interact. Our analysis yields four key findings: 1. Larger models consistently demonstrate superior compute and data efficiency. 2. The relationship between model performance and training resources follows a predictive power-law across both base and instruction-tuned models. 3. RL learning efficiency exhibits a latent saturation trend with increasing model scale. 4. In data-constrained regimes, performance is primarily driven by the total volume of training data rather than sample uniqueness. These results offer practical guidelines for scaling reasoning capabilities through reinforcement learning post-training.
2025
The Essence of Contextual Understanding in Theory of Mind: A Study on Question Answering with Story Characters
Chulun Zhou | Qiujing Wang | Mo Yu | Xiaoqian Yue | Rui Lu | Jiangnan Li | Yifan Zhou | Shunchi Zhang | Jie Zhou | Wai Lam
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Chulun Zhou | Qiujing Wang | Mo Yu | Xiaoqian Yue | Rui Lu | Jiangnan Li | Yifan Zhou | Shunchi Zhang | Jie Zhou | Wai Lam
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Theory-of-Mind (ToM) is a fundamental psychological capability that allows humans to understand and interpret the mental states of others. Humans infer others’ thoughts by integrating causal cues and indirect clues from broad contextual information, often derived from past interactions. In other words, human ToM heavily relies on the understanding about the backgrounds and life stories of others. Unfortunately, this aspect is largely overlooked in existing benchmarks for evaluating machines’ ToM capabilities, due to their usage of short narratives without global context, especially personal background of characters. In this paper, we verify the importance of comprehensive contextual understanding about personal backgrounds in ToM and assess the performance of LLMs in such complex scenarios. To achieve this, we introduce CharToM-QA benchmark, comprising 1,035 ToM questions based on characters from classic novels. Our human study reveals a significant disparity in performance: the same group of educated participants performs dramatically better when they have read the novels compared to when they have not. In parallel, our experiments on state-of-the-art LLMs, including the very recent o1 and DeepSeek-R1 models, show that LLMs still perform notably worse than humans, despite that they have seen these stories during pre-training. This highlights the limitations of current LLMs in capturing the nuanced contextual information required for ToM reasoning.
Search
Fix author
Co-authors
- Tianming Liu 2
- Yohannes Abate 1
- Lei Bai 1
- Chao Cao 1
- Junhao Chen 1
- Ling Chen 1
- Zhaojun Ding 1
- Yutao Fan 1
- Hejia Geng 1
- Qiang He 1
- Hanqi Jiang 1
- Wai Lam 1
- Jiangnan Li 1
- Yiwei Li 1
- Zhong-Zhi Li 1
- Jin Lu 1
- Rui Lu 1
- Yi Pan 1
- Bolun Sun 1
- Zelin Tan 1
- Philip Torr 1
- Guancheng Wan 1
- Qiujing Wang 1
- Xiangyuan Xue 1
- Zhenfei Yin 1
- Weihang You 1
- Mo Yu 1
- Xiaohang Yu 1
- Xiaoqian Yue 1
- Chen Zhang 1
- Guibin Zhang 1
- Lu Zhang 1
- Mulei Zhang 1
- Ruidong Zhang 1
- Shunchi Zhang 1
- Zaibin Zhang 1
- Huaqin Zhao 1
- Chulun Zhou 1
- Heng Zhou 1
- Jie Zhou 1