Wei Cheng
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2026
DeepSieve: Information Sieving via LLM-as-a-Knowledge-Router
Minghao Guo | Qingcheng Zeng | Xujiang Zhao | Yanchi Liu | Wenchao Yu | Mengnan Du | Haifeng Chen | Wei Cheng
Findings of the Association for Computational Linguistics: EACL 2026
Minghao Guo | Qingcheng Zeng | Xujiang Zhao | Yanchi Liu | Wenchao Yu | Mengnan Du | Haifeng Chen | Wei Cheng
Findings of the Association for Computational Linguistics: EACL 2026
Large Language Models (LLMs) excel at many reasoning tasks but struggle with knowledge-intensive queries due to their inability to dynamically access up-to-date or domain-specific information. Retrieval-Augmented Generation (RAG) has emerged as a promising solution, enabling LLMs to ground their responses in external sources. However, existing RAG methods lack fine-grained control over both the query and source sides, often resulting in noisy retrieval and shallow reasoning. In this work, we introduce DeepSieve, an agentic RAG framework that incorporates information sieving via LLM-as-a-knowledge-router. DeepSieve decomposes complex queries into structured sub-questions and recursively routes each to the most suitable knowledge source, filtering irrelevant information through a multi-stage distillation process. Our design emphasizes modularity, transparency, and adaptability, leveraging recent advances in agentic system design. Experiments on multi-hop QA tasks across heterogeneous sources demonstrate improved reasoning depth, retrieval precision, and interpretability over conventional RAG approaches.
Multi-Agent Procedural Graph Extraction with Structural and Logical Refinement
Wangyang Ying | Yanchi Liu | Xujiang Zhao | Wei Cheng | Zhengzhang Chen | Wenchao Yu | Yanjie Fu | Haifeng Chen
Findings of the Association for Computational Linguistics: EACL 2026
Wangyang Ying | Yanchi Liu | Xujiang Zhao | Wei Cheng | Zhengzhang Chen | Wenchao Yu | Yanjie Fu | Haifeng Chen
Findings of the Association for Computational Linguistics: EACL 2026
Automatically extracting workflows as procedural graphs from natural language is a promising yet underexplored task that requires ensuring both structural validity and logical alignment. Recent advances in large language models (LLMs) show potential for graph extraction, but often yield ill-formed structures or misinterpret logical constructs such as gateways. We introduce , a multi-agent framework that treats procedural graph extraction as a multi-round reasoning process with structural and logical refinement agents. The framework operates in three iterative stages: (1) an LLM-based graph extraction phase, (2) a structural feedback phase where a simulation agent diagnoses and explains structural issues, and (3) a logical feedback phase where a semantic agent aligns semantics between flow logic and linguistic cues in the source text. Important feedback is prioritized and expressed in natural language, which is injected into the next-round prompt, enabling interpretable and controllable refinement. This modular design allows agents to target distinct error types without supervision or parameter updates. Experiments demonstrate that achieves substantial improvements in both structural correctness and logical consistency over strong baselines.
When Evolution Meets Momentum: Orchestrating Goal-oriented and Process-oriented reasoning for LLM Inference Scaling
Mingyu Jin | Haifeng Chen | Yuanzhou Chen | Jonathan Light | Wenchao Yu | Wei Cheng
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Mingyu Jin | Haifeng Chen | Yuanzhou Chen | Jonathan Light | Wenchao Yu | Wei Cheng
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Large language models (LLMs) have demonstrated strong reasoning ability when given additional compute at inference time. However, existing inference-time scaling methods are fundamentally limited by their design. On the one hand, goal-oriented approaches, such as Line or Tree Search, refine candidate solutions using previous feedback but are vulnerable to sequential dependence, often collapsing into suboptimal reasoning trajectories. On the other hand, process-oriented approaches such as Best-of-N sampling encourage diversity through random exploration but lack feedback mechanisms, leading to inefficient computation allocation and unguided search. In this work, we propose EvoMo, a novel inference-time scaling approach that unifies both paradigms by embedding a globally evolving strategy pool into MCTS, where each node expansion selects reasoning strategies under an -soft policy. To further avoid stagnation in familiar strategies, we introduce a momentum-based optimization mechanism that monitors similarity among generated solutions and encourages the exploration of underutilized strategies. We also present a theoretical analysis of the effectiveness of the proposed momentum mechanism by modeling it as a self-evolving pool of actions. Across benchmarks, EvoMo reveals significant performance gains over SOTA inference scaling methods. We observe competitive performance, like in APPS and CodeContests, with up to a 4.5% and 3.63% relative gain in Pass@K compared to the leading baseline within 40 search-budget, highlighting the potential of hybrid evolutionary search as a general paradigm for test-time scaling.
MetaCaster: Meta-Harness-Optimized Agent for End-to-End Few-Shot Learning of Lightweight Time Series Forecasters
ChengAo Shen | Wenchao Yu | Fangyu Wu | Dongjin Song | Hanghang Tong | Dongsheng Luo | Wei Cheng | Haifeng Chen | Jingchao Ni
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
ChengAo Shen | Wenchao Yu | Fangyu Wu | Dongjin Song | Hanghang Tong | Dongsheng Luo | Wei Cheng | Haifeng Chen | Jingchao Ni
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Time series forecasting (TSF) is evolving toward multimodal and agentic settings, yet using foundation models remains uneconomical in resource-constrained scenarios, where compact, specialized forecasters are more desirable. However, lightweight forecasters typically require substantial training data, limiting their use in domains with scarce, slowly accumulated, or privacy-sensitive time series. To address this dilemma, we investigate the challenging problem of few-shot learning for lightweight forecasters. We propose MetaCaster, a meta-harness-optimized multi-agent framework that uses agentic data generation to automatically train specialized lightweight forecasters from only a few examples and textual contexts. Our work highlights a new TSF paradigm in which agents act not as forecasters but as intermediary engineers that prepare efficient, task-specific forecasters for deployment. Experiments on 18 datasets, 23 state-of-the-art lightweight forecasters, and 14 baselines demonstrate that MetaCaster achieves both data efficiency and computational efficiency while maintaining high-quality TSF performance.
Uncertainty-Aware Test-Time Search for Optimization Problem Solving
Linlin Yu | Xujiang Zhao | Dong Li | Yanchi Liu | Wei Cheng | Zhengzhang Chen | Chen Zhao | Feng Chen | Haifeng Chen
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Linlin Yu | Xujiang Zhao | Dong Li | Yanchi Liu | Wei Cheng | Zhengzhang Chen | Chen Zhao | Feng Chen | Haifeng Chen
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Automatically solving optimization problems from natural language descriptions with both efficiency and reliability is highly desirable but remains challenging. Language model hallucinations and the limited availability of labeled datasets often result in misaligned formulations, code errors, and feasibility failures We propose UMCTS, an Uncertainty-aware Monte Carlo Tree Search framework that combines the language understanding capability of large language models with the reliability of well-established solvers. UMCTS structures the solution process into four stages: global instruction, assumptions, mathematical formulation, and solver code generation. It employs Monte Carlo Tree Search with semantic-equivalence pruning, prior-guided exploration, and solver-based feasibility checks. An LLM judge provides numerical reward signals, qualitative error information, and uncertainty estimates. These signals are backpropagated to guide the search and flag unreliable outputs. Across six public benchmarks, UMCTS achieves state-of-the-art solution accuracy, improves efficiency by reducing token usage.
Stop When Enough: Adaptive Early-Stopping for Chain-of-Thought Reasoning
Renliang Sun | Wei Cheng | Dawei Li | Haifeng Chen | Wei Wang
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Renliang Sun | Wei Cheng | Dawei Li | Haifeng Chen | Wei Wang
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Chain-of-Thought (CoT) reasoning has driven recent gains of large language models (LLMs) on reasoning-intensive tasks by externalizing intermediate steps. However, excessive or redundant reasoning — so-called overthinking — can increase inference costs and lead LLMs toward incorrect conclusions. In this paper, we present REFRAIN ( ̲REFlective- ̲Redundancy for ̲Adaptive ̲INference), a training-free framework that adaptively determines when to stop reasoning to mitigate overthinking. REFRAIN integrates a two-stage stop discriminator to identify reflective yet redundant reasoning and a sliding-window Upper Confidence Bound (SW-UCB) multi-armed bandit controller to dynamically adjust stopping thresholds according to problem difficulty without supervision or fine-tuning. Across four representative benchmarks and two model families, REFRAIN reduces token usage by 20-55% while maintaining or improving accuracy compared to standard CoT prompting. Extensive ablation and robustness analyses demonstrate its stability across models, scorers, and prompt variations. In summary, our findings highlight when-to-stop as a new and practical axis of test-time scaling — enabling models to reason not just more, but just enough.
2025
MixLLM: Dynamic Routing in Mixed Large Language Models
Xinyuan Wang | Yanchi Liu | Wei Cheng | Xujiang Zhao | Zhengzhang Chen | Wenchao Yu | Yanjie Fu | Haifeng Chen
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Xinyuan Wang | Yanchi Liu | Wei Cheng | Xujiang Zhao | Zhengzhang Chen | Wenchao Yu | Yanjie Fu | Haifeng Chen
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Large Language Models (LLMs) exhibit potential artificial generic intelligence recently, however, their usage is costly with high response latency. Given mixed LLMs with their own strengths and weaknesses, LLM routing aims to identify the most suitable model for each query in the stream to maximize response quality and minimize cost and latency. However, the challenges involve: (1) dynamic trade-offs among quality, cost, and latency; (2) enabling continual learning in deployed systems; and (3) navigating a varying (e.g., new LLM addition or old LLM removal) set of LLM candidates over time. To bridge these gaps, we develop MixLLM, a dynamic contextual-bandit-based routing system for query-LLM assignment. Specifically, we first leverage query tags to enhance query embeddings for the routing task. Next, we design lightweight prediction models to estimate the response qualities and costs of queries over LLMs. We then devise a meta-decision maker to choose the query-LLM assignments to best tradeoff response quality, cost, and latency. Finally, the system benefits from continual training, allowing it to adapt to evolving queries and user feedback over time. Our extensive experiments show that MixLLM achieves the best trade-offs in response quality, cost, and latency (97.25% of GPT-4’s quality at 24.18% of the cost under the time constraint).
Position Really Matters: Towards a Holistic Approach for Prompt Tuning
Xianjun Yang | Wei Cheng | Xujiang Zhao | Wenchao Yu | Linda Ruth Petzold | Haifeng Chen
Findings of the Association for Computational Linguistics: NAACL 2025
Xianjun Yang | Wei Cheng | Xujiang Zhao | Wenchao Yu | Linda Ruth Petzold | Haifeng Chen
Findings of the Association for Computational Linguistics: NAACL 2025
Prompt tuning is highly effective in efficiently extracting knowledge from foundation models, encompassing both language, vision, and vision-language models. However, the efficacy of employing fixed soft prompts with a predetermined position for concatenation with inputs for all instances, irrespective of their inherent disparities, remains uncertain. Variables such as the position, length, and representations of prompts across diverse instances and tasks can substantially influence the performance of prompt tuning. We first provide a theoretical analysis, revealing that optimizing the position of the prompt to encompass the input can capture additional semantic information that traditional prefix or postfix prompt tuning methods fail to capture. Then, we present a holistic parametric prompt tuning strategy that dynamically determines different factors of prompts based on specific tasks or instances. Experimental results underscore the significant performance improvement achieved by dynamic prompt tuning across a wide range of tasks, including NLP, vision recognition, and vision-language tasks. Furthermore, we establish the universal applicability of our approach under full-data, few-shot, and multitask settings.
Uncertainty Propagation on LLM Agent
Qiwei Zhao | Dong Li | Yanchi Liu | Wei Cheng | Yiyou Sun | Mika Oishi | Takao Osaki | Katsushi Matsuda | Huaxiu Yao | Chen Zhao | Haifeng Chen | Xujiang Zhao
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Qiwei Zhao | Dong Li | Yanchi Liu | Wei Cheng | Yiyou Sun | Mika Oishi | Takao Osaki | Katsushi Matsuda | Huaxiu Yao | Chen Zhao | Haifeng Chen | Xujiang Zhao
Proceedings of the 63rd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Large language models (LLMs) integrated into multi-step agent systems enable complex decision-making processes across various applications. However, their outputs often lack reliability, making uncertainty estimation crucial. Existing uncertainty estimation methods primarily focus on final-step outputs, which fail to account for cumulative uncertainty over the multi-step decision-making process and the dynamic interactions between agents and their environments. To address these limitations, we propose SAUP (Situation Awareness Uncertainty Propagation), a novel framework that propagates uncertainty through each step of an LLM-based agent’s reasoning process. SAUP incorporates situational awareness by assigning situational weights to each step’s uncertainty during the propagation. Our method, compatible with various one-step uncertainty estimation techniques, provides a comprehensive and accurate uncertainty measure. Extensive experiments on benchmark datasets demonstrate that SAUP significantly outperforms existing state-of-the-art methods, achieving up to 20% improvement in AUROC.
2024
TrustAgent: Towards Safe and Trustworthy LLM-based Agents
Wenyue Hua | Xianjun Yang | Mingyu Jin | Zelong Li | Wei Cheng | Ruixiang Tang | Yongfeng Zhang
Findings of the Association for Computational Linguistics: EMNLP 2024
Wenyue Hua | Xianjun Yang | Mingyu Jin | Zelong Li | Wei Cheng | Ruixiang Tang | Yongfeng Zhang
Findings of the Association for Computational Linguistics: EMNLP 2024
The rise of LLM-based agents shows great potential to revolutionize task planning, capturing significant attention. Given that these agents will be integrated into high-stake domains, ensuring their reliability and safety is crucial. This paper presents an Agent-Constitution-based agent framework, TrustAgent, with a particular focus on improving the LLM-based agent safety. The proposed framework ensures strict adherence to the Agent Constitution through three strategic components: pre-planning strategy which injects safety knowledge to the model before plan generation, in-planning strategy which enhances safety during plan generation, and post-planning strategy which ensures safety by post-planning inspection. Our experimental results demonstrate that the proposed framework can effectively enhance an LLM agent’s safety across multiple domains by identifying and mitigating potential dangers during the planning. Further analysis reveals that the framework not only improves safety but also enhances the helpfulness of the agent. Additionally, we highlight the importance of the LLM reasoning ability in adhering to the Constitution. This paper sheds light on how to ensure the safe integration of LLM-based agents into human-centric environments. Data and code are available at https://anonymous.4open.science/r/TrustAgent-06DC.
A Survey on Detection of LLMs-Generated Content
Xianjun Yang | Liangming Pan | Xuandong Zhao | Haifeng Chen | Linda Ruth Petzold | William Yang Wang | Wei Cheng
Findings of the Association for Computational Linguistics: EMNLP 2024
Xianjun Yang | Liangming Pan | Xuandong Zhao | Haifeng Chen | Linda Ruth Petzold | William Yang Wang | Wei Cheng
Findings of the Association for Computational Linguistics: EMNLP 2024
The burgeoning capabilities of advanced large language models (LLMs) such as ChatGPT have led to an increase in synthetic content generation with implications across a variety of sectors, including media, cybersecurity, public discourse, and education. As such, the ability to detect LLMs-generated content has become of paramount importance. We aim to provide a detailed overview of existing detection strategies and benchmarks, scrutinizing their differences and identifying key challenges and prospects in the field, advocating for more adaptable and robust models to enhance detection accuracy. We also posit the necessity for a multi-faceted approach to defend against various attacks to counter the rapidly advancing capabilities of LLMs. To the best of our knowledge, this work is the first comprehensive survey on the detection in the era of LLMs. We hope it will provide a broad understanding of the current landscape of LLMs-generated content detection, and we have maintained a website to consistently update the latest research as a guiding reference for researchers and practitioners.
InfuserKI: Enhancing Large Language Models with Knowledge Graphs via Infuser-Guided Knowledge Integration
Fali Wang | Runxue Bao | Suhang Wang | Wenchao Yu | Yanchi Liu | Wei Cheng | Haifeng Chen
Findings of the Association for Computational Linguistics: EMNLP 2024
Fali Wang | Runxue Bao | Suhang Wang | Wenchao Yu | Yanchi Liu | Wei Cheng | Haifeng Chen
Findings of the Association for Computational Linguistics: EMNLP 2024
Large Language Models (LLMs) have achieved exceptional capabilities in open generation across various domains, yet they encounter difficulties with tasks that require intensive knowledge. To address these challenges, methods for integrating knowledge have been developed, which augment LLMs with domain-specific knowledge graphs through external modules. These approaches, however, face data inefficiency issues as they necessitate the processing of both known and unknown knowledge for fine-tuning. Thus, our research focuses on a novel problem: efficiently integrating unknown knowledge into LLMs without unnecessary overlap of known knowledge. A risk of introducing new knowledge is the potential forgetting of existing knowledge. To mitigate this risk, we propose the innovative InfuserKI framework. This framework employs transformer internal states to determine when to enrich LLM outputs with additional information, effectively preventing knowledge forgetting. Performance evaluations using the UMLS-2.5k and MetaQA domain knowledge graphs reveal that InfuserKI not only successfully integrates new knowledge but also outperforms state-of-the-art baselines, reducing knowledge forgetting by 9% and 6%, respectively.
Large Language Models Can Be Contextual Privacy Protection Learners
Yijia Xiao | Yiqiao Jin | Yushi Bai | Yue Wu | Xianjun Yang | Xiao Luo | Wenchao Yu | Xujiang Zhao | Yanchi Liu | Quanquan Gu | Haifeng Chen | Wei Wang | Wei Cheng
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
Yijia Xiao | Yiqiao Jin | Yushi Bai | Yue Wu | Xianjun Yang | Xiao Luo | Wenchao Yu | Xujiang Zhao | Yanchi Liu | Quanquan Gu | Haifeng Chen | Wei Wang | Wei Cheng
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
The proliferation of Large Language Models (LLMs) has driven considerable interest in fine-tuning them with domain-specific data to create specialized language models. Nevertheless, such domain-specific fine-tuning data often contains contextually sensitive personally identifiable information (PII). Direct fine-tuning LLMs on this data without privacy protection poses a risk of data leakage of sensitive PII during inference time. To address this challenge, we introduce Contextual Privacy Protection Language Models (CPPLM), a novel paradigm for fine-tuning LLMs that effectively injects domain-specific knowledge while safeguarding inference-time data privacy. Our work offers a theoretical analysis for model design and delves into various techniques such as corpus curation, penalty-based unlikelihood in training loss, and instruction-based tuning, etc. Extensive experiments across diverse datasets and scenarios demonstrate the effectiveness of our approaches. In particular, instruction tuning with both positive and negative examples, stands out as a promising method, effectively protecting private data while enhancing the model’s knowledge. Our work underscores the potential for Large Language Models as robust contextual privacy protection learners. The complete code and data for the work can be found at https://github.com/Yijia-Xiao/PPLM.
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Co-authors
- Haifeng Chen 12
- Wenchao Yu 8
- Yanchi Liu 7
- Xujiang Zhao 7
- Xianjun Yang 4
- Zhengzhang Chen 3
- Yanjie Fu 2
- Mingyu Jin 2
- Dong Li 2
- Linda Ruth Petzold 2
- Wei Wang 2
- Chen Zhao 2
- Yushi Bai 1
- Runxue Bao 1
- Feng Chen 1
- Yuanzhou Chen 1
- Mengnan Du 1
- Quanquan Gu 1
- Minghao Guo (郭铭昊) 1
- Wenyue Hua 1
- Yiqiao Jin 1
- Dawei Li 1
- Zelong Li 1
- Jonathan Light 1
- Dongsheng Luo 1
- Xiao Luo 1
- Katsushi Matsuda 1
- Jingchao Ni 1
- Mika Oishi 1
- Takao Osaki 1
- Liangming Pan 1
- ChengAo Shen 1
- Dongjin Song 1
- Renliang Sun 1
- Yiyou Sun 1
- Ruixiang Tang 1
- Hanghang Tong 1
- Fali Wang 1
- Suhang Wang 1
- William Yang Wang 1
- Xinyuan Wang 1
- Fangyu Wu 1
- Yue Wu 1
- Yijia Xiao 1
- Huaxiu Yao 1
- Wangyang Ying 1
- Linlin Yu 1
- Qingcheng Zeng 1
- Yongfeng Zhang 1
- Qiwei Zhao 1
- Xuandong Zhao 1