Yu Feng
Author directoryPapers on this page may belong to the following people: Yu Feng, Yu Feng, Yu Feng
2026
SearchAtlas: Analyzing Agentic Search Strategies via Evidential Query Graphs
Jiacheng Sang | Mengyuan Li | Sanxing Chen | Yukun Huang | Yu Feng | Bhuwan Dhingra
Findings of the Association for Computational Linguistics: EMNLP 2026
Jiacheng Sang | Mengyuan Li | Sanxing Chen | Yukun Huang | Yu Feng | Bhuwan Dhingra
Findings of the Association for Computational Linguistics: EMNLP 2026
LLM search agents are often evaluated on final-answer accuracy, overlooking the process. Analyzing a search strategy requires understanding how credible evidence is retrieved to address question constraints. This valuable information is buried in raw search trajectories that are long and difficult to parse. We introduce SearchAtlas, a framework that converts search trajectories into structured graphs whose edges represent how evidence is propagated across the reasoning trace, from the query that retrieves it to the final answer. Our automated parsing pipeline achieves a mean edge F₁ of 86.0% against human-annotated graphs and remains consistent across repeated runs. We analyze five search agents on three benchmarks, which reveal systematic differences in search scale and evidence aggregation across agents and benchmarks. SearchAtlas exposes fragmented answer support, question constraints that do not reach the answer, and unverified parametric knowledge entering the response. These process failures are strongly associated with incorrect answers, even more so than an LLM judge given either the raw trajectory or the ordered query list, suggesting that the constructed graphs provide useful interpretability. Moreover, an audit of cases in which process diagnostic scores disagree with final-answer correctness shows that they capture information not reducible to answer accuracy.
Skill Reuse as Compression in Agentic RL
Zhikun Xu | Yu Feng | Jacob Dineen | Taiwei Shi | Jieyu Zhao | Ben Zhou
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Zhikun Xu | Yu Feng | Jacob Dineen | Taiwei Shi | Jieyu Zhao | Ben Zhou
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Large language model agents trained with reinforcement learning (RL) often learn brittle, task-specific shortcuts. We hypothesize that agents generalize better when their successful trajectories are structurally compressible, decomposed into a small set of reusable abstract patterns. To formalize this, we introduce ReuseRL, which grounds agentic RL in the Minimum Description Length (MDL) principle. ReuseRL extracts a shared skill dictionary from successful trajectories and augments the RL objective with a segmentation cost, explicitly penalizing idiosyncratic behaviors that encode poorly. We prove a PAC-Bayes generalization bound for this objective. Across ALFWorld, TextWorld-Cooking, and Countdown-Stepwise, ReuseRL improves in- and out-of-distribution success over vanilla GRPO and strong round-length baselines.
On the (In-)Security of the Shuffling Defense in the Transformer Secure Inference
Zhengyi Li | Yakai Wang | Jingwen Leng | Kang Yang | Yu Yu | Jiaping Gui | Yu Feng | Ning Liu | Minyi Guo
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Zhengyi Li | Yakai Wang | Jingwen Leng | Kang Yang | Yu Yu | Jiaping Gui | Yu Feng | Ning Liu | Minyi Guo
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
For Transformer models, cryptographically secure inference ensures that the client learns only the final output, while the server learns nothing about the client’s input. However, securely computing nonlinear layers remains a major efficiency bottleneck due to the substantial communication rounds and data transmission required. To address this issue, prior works reveal intermediate activations to the client, allowing nonlinear operations to be computed in plaintext. Although this approach significantly improves efficiency, exposing activations enables adversaries to extract model weights. To mitigate this risk, existing works employ a shuffling defense that reveals only randomly permuted activations to the client. In this work, we show that the shuffling defense is not as robust as previously claimed. We propose an attack that aligns differently shuffled activations to a common permutation and subsequently exploits them to extract model weights. Experiments on Pythia-70m and GPT-2 demonstrate that the proposed attack can align shuffled activations with mean squared errors ranging from 10-9 to 10-6. With a query cost of approximately $1, the adversary can recover model weights with L1-norm differences ranging from 10-4 to 10-2 compared to the oracle weights.
2025
Rethinking LLM Uncertainty: A Multi-Agent Approach to Estimating Black-Box Model Uncertainty
Yu Feng | Phu Mon Htut | Zheng Qi | Wei Xiao | Manuel Mager | Nikolaos Pappas | Kishaloy Halder | Yang Li | Yassine Benajiba | Dan Roth
Findings of the Association for Computational Linguistics: EMNLP 2025
Yu Feng | Phu Mon Htut | Zheng Qi | Wei Xiao | Manuel Mager | Nikolaos Pappas | Kishaloy Halder | Yang Li | Yassine Benajiba | Dan Roth
Findings of the Association for Computational Linguistics: EMNLP 2025
Quantifying uncertainty in black-box LLMs is vital for reliable responses and scalable oversight. Existing methods, which gauge a model’s uncertainty through evaluating self-consistency in responses to the target query, can be misleading: an LLM may confidently provide an incorrect answer to a target query, yet give a confident and accurate answer to that same target query when answering a knowledge-preserving perturbation of the query. We systematically analyze the model behaviors and demonstrate that this discrepancy stems from suboptimal retrieval of parametric knowledge, often due to contextual biases that prevent consistent access to stored knowledge. We then introduce DiverseAgentEntropy, a novel, theoretically-grounded method employing multi-agent interaction across diverse query variations for uncertainty estimation of black-box LLMs. This approach more accurately assesses an LLM’s true uncertainty and improves hallucination detection, outperforming existing self-consistency based techniques.
2024
Vector Poetics: Parallel Couplet Detection in Classical Chinese Poetry
Maciej Kurzynski | Xiaotong Xu | Yu Feng
Proceedings of the 4th International Conference on Natural Language Processing for Digital Humanities
Maciej Kurzynski | Xiaotong Xu | Yu Feng
Proceedings of the 4th International Conference on Natural Language Processing for Digital Humanities
This paper explores computational approaches for detecting parallelism in classical Chinese poetry, a rhetorical device where two verses mirror each other in syntax, meaning, tone, and rhythm. We experiment with five classification methods: (1) verb position matching, (2) integrated semantic, syntactic, and word-segmentation analysis, (3) difference-based character embeddings, (4) structured examples (inner/outer couplets), and (5) GPT-guided classification. We use a manually annotated dataset, containing 6,125 pentasyllabic couplets, to evaluate performance. The results indicate that parallelism detection poses a significant challenge even for powerful LLMs such as GPT-4o, with the highest F1 score below 0.72. Nevertheless, each method contributes valuable insights into the art of parallelism in Chinese poetry, suggesting a new understanding of parallelism as a verbal expression of principal components in a culturally defined vector space.
2021
A Pretraining Numerical Reasoning Model for Ordinal Constrained Question Answering on Knowledge Base
Yu Feng | Jing Zhang | Gaole He | Wayne Xin Zhao | Lemao Liu | Quan Liu | Cuiping Li | Hong Chen
Findings of the Association for Computational Linguistics: EMNLP 2021
Yu Feng | Jing Zhang | Gaole He | Wayne Xin Zhao | Lemao Liu | Quan Liu | Cuiping Li | Hong Chen
Findings of the Association for Computational Linguistics: EMNLP 2021
Knowledge Base Question Answering (KBQA) is to answer natural language questions posed over knowledge bases (KBs). This paper targets at empowering the IR-based KBQA models with the ability of numerical reasoning for answering ordinal constrained questions. A major challenge is the lack of explicit annotations about numerical properties. To address this challenge, we propose a pretraining numerical reasoning model consisting of NumGNN and NumTransformer, guided by explicit self-supervision signals. The two modules are pretrained to encode the magnitude and ordinal properties of numbers respectively and can serve as model-agnostic plugins for any IR-based KBQA model to enhance its numerical reasoning ability. Extensive experiments on two KBQA benchmarks verify the effectiveness of our method to enhance the numerical reasoning ability for IR-based KBQA models.
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Co-authors
- Yassine Benajiba 1
- Hong Chen 1
- Sanxing Chen 1
- Bhuwan Dhingra 1
- Jacob Dineen 1
- Jiaping Gui 1
- Minyi Guo 1
- Kishaloy Halder 1
- Gaole He 1
- Phu Mon Htut 1
- Yukun Huang 1
- Maciej Kurzynski 1
- Jingwen Leng 1
- Cuiping Li 1
- Mengyuan Li (李梦媛) 1
- Yang Li 1
- Zhengyi Li 1
- Lemao Liu 1
- Ning Liu 1
- Quan Liu 1
- Manuel Mager 1
- Nikolaos Pappas 1
- Zheng Qi 1
- Dan Roth 1
- Jiacheng Sang 1
- Taiwei Shi 1
- Yakai Wang 1
- Wei Xiao 1
- Xiaotong Xu 1
- Zhikun Xu 1
- Kang Yang 1
- Yu Yu 1
- Jing Zhang 1
- Jieyu Zhao 1
- Wayne Xin Zhao 1
- Ben Zhou 1