Junfeng Ran


2025

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LongAttn: Selecting Long-context Training Data via Token-level Attention
Longyun Wu | Dawei Zhu | Guangxiang Zhao | Zhuocheng Yu | Junfeng Ran | Xiangyu Wong | Lin Sun | Sujian Li
Findings of the Association for Computational Linguistics: ACL 2025

With the development of large language models (LLMs), there has been an increasing need for significant advancements in handling long contexts. To enhance long-context capabilities, constructing high-quality training data with **long-range dependencies** is crucial. Existing methods to select long-context data often rely on sentence-level analysis,which can be greatly optimized in both performance and efficiency. In this paper, we propose a novel token-level framework, ​**LongAttn**​, which leverages the self-attention mechanism of LLMs to measure the **long-range dependencies** for the data. By calculating token-level dependency strength and distribution uniformity of token scores, LongAttn effectively quantifies ​**long-range dependencies**​, enabling more accurate and efficient data selection. We filter **LongABC-32K** from open-source long-context datasets (ArXiv, Book, and Code). Through our comprehensive experiments, LongAttn has demonstrated its excellent ​**effectiveness**​, ​**scalability**​, and ​**efficiency**​. We will release our code and the high-quality long-context dataset **LongABC-32K** in the future.

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Chain-of-Thought Matters: Improving Long-Context Language Models with Reasoning Path Supervision
Dawei Zhu | Xiyu Wei | Guangxiang Zhao | Wenhao Wu | Haosheng Zou | Junfeng Ran | XWang | Lin Sun | Xiangzheng Zhang | Sujian Li
Findings of the Association for Computational Linguistics: EMNLP 2025

Recent advances in Large Language Models (LLMs) have highlighted the challenge of handling long-context tasks, where models need to reason over extensive input contexts to aggregate target information. While Chain-of-Thought (CoT) prompting has shown promise for multi-step reasoning, its effectiveness for long-context scenarios remains underexplored. Through systematic investigation across diverse tasks, we demonstrate that CoT’s benefits generalize across most long-context scenarios and amplify with increasing context length. Motivated by this, we propose a process-supervised framework that teaches models to generate high-quality reasoning paths for enhanced long-context performance. Our framework incorporates a self-sampling mechanism to bootstrap reasoning paths and a novel quality assessment protocol specifically designed for long-context scenarios. This protocol evaluates both answer correctness and process reliability, with the latter decomposed into source faithfulness and intrinsic consistency components for efficient and accurate assessment. Experimental results on various long-context benchmarks demonstrate the effectiveness of our approach, achieving significant improvements over outcome supervision baselines on both in-domain tasks (+13.6/+3.8 points for LLaMA/Qwen on MuSiQue) and cross-domain generalization (+9.3/+8.1 points on average across diverse QA tasks). Our code, data and trained models will be released upon acceptance.

2024

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FaGANet: An Evidence-Based Fact-Checking Model with Integrated Encoder Leveraging Contextual Information
Weiyao Luo | Junfeng Ran | Zailong Tian | Sujian Li | Zhifang Sui
Proceedings of the 2024 Joint International Conference on Computational Linguistics, Language Resources and Evaluation (LREC-COLING 2024)

In the face of the rapidly growing spread of false and misleading information in the real world, manual evidence-based fact-checking efforts become increasingly challenging and time-consuming. In order to tackle this issue, we propose FaGANet, an automated and accurate fact-checking model that leverages the power of sentence-level attention and graph attention network to enhance performance. This model adeptly integrates encoder-only models with graph attention network, effectively fusing claims and evidence information for accurate identification of even well-disguised data. Experiment results showcase the significant improvement in accuracy achieved by our FaGANet model, as well as its state-of-the-art performance in the evidence-based fact-checking task. We release our code and data in https://github.com/WeiyaoLuo/FaGANet.