Lei Feng
Author directory2026
Beyond Next-Observation Prediction: Agent-Authored World Modeling for Sequential Decision Making
Guangfeng Cai | Kaibing Yang | Shuo He | Yu Li | Shengtian Yang | Jiaqi Lv | Lei Feng
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Guangfeng Cai | Kaibing Yang | Shuo He | Yu Li | Shengtian Yang | Jiaqi Lv | Lei Feng
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Recent studies on world modeling for Large Language Model (LLM) agents typically formulate the learning objective as next-observation prediction. However, this objective ties supervision to what a transition happens to reveal, which may omit the dynamics most relevant to the agent’s current decision. To bridge this gap, we propose Agent-Authored World Modeling (AAWM), a training procedure that constructs supervision from the policy’s own decision needs. Specifically, at each state, the agent identifies what it needs to understand about the environment before acting. These needs drive the retrieval of relevant transition evidence across trajectories, which is then synthesized into training targets that capture decision-oriented dynamics instead of reconstructing the next observation. This aligns the training objective with the dynamics the policy needs before acting, not with the contents of the next observation. Experimental results validate the effectiveness of AAWM across multiple environments and training settings. These results show that decision-aware world-model targets provide a more effective learning signal than next-observation prediction.
Generation-Gated Cascaded Routing for Large Language Models
Yanqiu Xu | Han Luo | Lei Feng
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Yanqiu Xu | Han Luo | Lei Feng
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Cost-effective deployment of large language models (LLMs) often relies on routing each query to either a low-cost local model or a stronger expert model. Existing routers typically decide either before generation, which is cheap but cannot observe the local model’s answer, or after generation, which provides a stronger correctness signal but incurs additional generation cost. We argue that this dichotomy overlooks a third option: treating local generation itself as an optional information-acquisition action. To this end, we propose Generation-Gated Cascaded Routing for Large Language Models (GenGate), a lightweight fine-tuning method that trains a local LLM to internalize cascaded routing decisions while preserving its generation capability. A Bellman-motivated prior gate first decides whether to generate a local attempt. If an attempt is produced, a correctness-supervised posterior gate then decides whether to submit it or defer to the expert model. Both decisions are expressed through action-token probabilities in the same model, requiring no external router or auxiliary classifier at inference time. Compared with routers that decide strictly before or after local generation, GenGate reduces joint deployment cost while maintaining competitive routing accuracy across task domains, preserving the benefits of posterior routing without requiring local generation for every query.
2025
Towards Reverse Engineering of Language Models: A Survey
Xinpeng Ti | Wentao Ye | Zhifang Zhang | Junbo Zhao | Chang Yao | Lei Feng | Haobo Wang
Findings of the Association for Computational Linguistics: EMNLP 2025
Xinpeng Ti | Wentao Ye | Zhifang Zhang | Junbo Zhao | Chang Yao | Lei Feng | Haobo Wang
Findings of the Association for Computational Linguistics: EMNLP 2025
With the continuous development of language models and the widespread availability of various types of accessible interfaces, large language models (LLMs) have been applied to an increasing number of fields. However, due to the vast amounts of data and computational resources required for model development, protecting the model’s parameters and training data has become an urgent and crucial concern. Due to the revolutionary training and application paradigms of LLMs, many new attacks on language models have emerged in recent years. In this paper, we define these attacks as “reverse engineering” (RE) techniques on LMs and aim to provide an in-depth analysis of reverse engineering of language models. We illustrate various methods of reverse engineering applied to different aspects of a model, while also providing an introduction to existing protective strategies. On the one hand, it demonstrates the vulnerabilities of even black box models to different types of attacks; on the other hand, it offers a more holistic perspective for the development of new protective strategies for models.
2024
Learning Geometry-Aware Representations for New Intent Discovery
Kai Tang | Junbo Zhao | Xiao Ding | Runze Wu | Lei Feng | Gang Chen | Haobo Wang
Proceedings of the 62nd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Kai Tang | Junbo Zhao | Xiao Ding | Runze Wu | Lei Feng | Gang Chen | Haobo Wang
Proceedings of the 62nd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
New intent discovery (NID) is an important problem for deploying practical dialogue systems, which trains intent classifiers on a semi-supervised corpus where unlabeled user utterances contain both known and novel intents. Most existing NID algorithms place hope on the sample similarity to cluster unlabeled corpus to known or new samples. Lacking supervision on new intents, we experimentally find the intent classifier fails to fully distinguish new intents since they tend to assemble into intertwined centers.To address this problem, we propose a novel GeoID framework that learns geometry-aware representations to maximally separate all intents. Specifically, we are motivated by the recent findings on Neural Collapse (NC) in classification tasks to derive optimal intent center structure. Meanwhile, we devise a dual pseudo-labeling strategy based on optimal transport assignments and semi-supervised clustering, ensuring proper utterances-to-center arrangement.Extensive results show that our GeoID method establishes a new state-of-the-art performance, achieving a +3.49% average accuracy improvement on three standardized benchmarking datasets. We also verify its usefulness in assisting large language models for improved in-context performance.