Problem Solving
Invoke Interfaces Only When Needed: Adaptive Invocation for Large Language Models in Question Answering
Zhao, Jihao, Zhou, Chunlai, Li, Daixuan, Zu, Shuaishuai, Qin, Biao
The collaborative paradigm of large and small language models (LMs) effectively balances performance and cost, yet its pivotal challenge lies in precisely pinpointing the moment of invocation when hallucinations arise in small LMs. Previous optimization efforts primarily focused on post-processing techniques, which were separate from the reasoning process of LMs, resulting in high computational costs and limited effectiveness. In this paper, we propose a practical invocation evaluation metric called AttenHScore, which calculates the accumulation and propagation of hallucinations during the generation process of small LMs, continuously amplifying potential reasoning errors. By dynamically adjusting the detection threshold, we achieve more accurate real-time invocation of large LMs. Additionally, considering the limited reasoning capacity of small LMs, we leverage uncertainty-aware knowledge reorganization to assist them better capture critical information from different text chunks. Extensive experiments reveal that our AttenHScore outperforms most baselines in enhancing real-time hallucination detection capabilities across multiple QA datasets, especially when addressing complex queries. Moreover, our strategies eliminate the need for additional model training and display flexibility in adapting to various transformer-based LMs.
Transformers Provably Learn Chain-of-Thought Reasoning with Length Generalization
Huang, Yu, Wen, Zixin, Singh, Aarti, Chi, Yuejie, Chen, Yuxin
The ability to reason lies at the core of artificial intelligence (AI), and challenging problems usually call for deeper and longer reasoning to tackle. A crucial question about AI reasoning is whether models can extrapolate learned reasoning patterns to solve harder tasks with longer chain-of-thought (CoT). In this work, we present a theoretical analysis of transformers learning on synthetic state-tracking tasks with gradient descent. We mathematically prove how the algebraic structure of state-tracking problems governs the degree of extrapolation of the learned CoT. Specifically, our theory characterizes the length generalization of transformers through the mechanism of attention concentration, linking the retrieval robustness of the attention layer to the state-tracking task structure of long-context reasoning. Moreover, for transformers with limited reasoning length, we prove that a recursive self-training scheme can progressively extend the range of solvable problem lengths. To our knowledge, we provide the first optimization guarantee that constant-depth transformers provably learn $\mathsf{NC}^1$-complete problems with CoT, significantly going beyond prior art confined in $\mathsf{TC}^0$, unless the widely held conjecture $\mathsf{TC}^0 \neq \mathsf{NC}^1$ fails. Finally, we present a broad set of experiments supporting our theoretical results, confirming the length generalization behaviors and the mechanism of attention concentration.
Introducing LongCat-Flash-Thinking: A Technical Report
Meituan LongCat Team, null, Gui, Anchun, Li, Bei, Tao, Bingyang, Zhou, Bole, Chen, Borun, Zhang, Chao, Zhang, Chao, Han, Chengcheng, Yang, Chenhui, Zhang, Chi, Peng, Chong, Zhang, Chuyu, Chen, Cong, Li, Fengcun, Xu, Gang, Lin, Guoyuan, Jiang, Hao, Liang, Hao, Fu, Haomin, Ma, Haoxiang, Liu, Hong, Hao, Hongyan, Tang, Hongyin, Zang, Hongyu, Ni, Hongzhi, Su, Hui, Liu, Jiahao, Li, Jiahuan, Liu, Jialin, Zhang, Jianfei, Xu, Jianhao, Wang, Jianing, Sun, Jiaqi, Zhang, Jiaqi, Shi, Jiarong, Yang, Jiawei, Wang, Jingang, Ding, Jinrui, Kuang, Jun, Xu, Jun, He, Ke, Zhang, Kefeng, Wang, Keheng, He, Keqing, Wei, Li, Shi, Liang, Qiu, Lin, Kong, Lingbin, Liu, Lingchuan, Guo, Linsen, An, Longfei, Xia, Mai, Zhou, Meng, Zhu, Mengshen, Pei, Peng, Jia, Pengcheng, Gu, Qi, Guo, Qi, Huang, Qiong, Chen, Quan, Weng, Quanchi, Weng, Rongxiang, Shao, Ruichen, Li, Rumei, Lei, Shanglin, Du, Shuai, Liu, Shuaikang, Zhou, Shuang, Hu, Shuhao, Xu, Siyu, Gong, Songshan, Liang, Tao, Hu, Tianhao, He, Wei, Shi, Wei, Wang, Wei, Wu, Wei, Zhuo, Wei, Tang, Weifeng, Shi, Wenjie, Zhu, Wenlong, Su, Xi, Liu, Xiangcheng, Xi, Xiangyu, Huang, Xiangzhou, Liu, Xiao, Jiang, Xiaochen, Shi, Xiaowei, Shi, Xiaowen, Li, Xiaoyu, Chen, Xin, Zhao, Xinyue, Huang, Xuan, Zhang, Xuemiao, Cao, Xuezhi, Cai, Xunliang, Zhang, Yajie, Chen, Yang, Liu, Yang, Liu, Yang, Zheng, Yang, Wang, Yaoming, Huo, Yaqi, Sun, Yerui, Lu, Yifan, Li, Yiyang, Xiao, Youshao, Lei, Yuanzhe, Xie, Yuchen, Sun, Yueqing, Zhang, Yufei, Wei, Yuhuai, Qian, Yulei, Zhao, Yunke, Ding, Yuqing, Jiang, Yuwei, Yang, Zhaohua, Chen, Zhengyu, Liu, Zhijian, Xia, Zhikang, Su, Zhongda, Li, Ziran, Wang, Ziwen, Zhuang, Ziyuan, Wang, Zongyu, Yang, Zunyuan
We present LongCat-Flash-Thinking, an efficient 560-billion-parameter open-source Mixture-of-Experts (MoE) reasoning model. Its advanced capabilities are cultivated through a meticulously crafted training process, beginning with long Chain-of-Thought (CoT) data cold-start and culminating in large-scale Reinforcement Learning (RL). We first employ a well-designed cold-start training strategy, which significantly enhances the reasoning potential and equips the model with specialized skills in both formal and agentic reasoning. Then, a core innovation is our domain-parallel training scheme, which decouples optimization across distinct domains (e.g., STEM, Code, Agentic) and subsequently fuses the resulting expert models into a single, nearly Pareto-optimal model. This entire process is powered by our Dynamic ORchestration for Asynchronous rollout (DORA) system, a large-scale RL framework that delivers a greater than threefold training speedup over synchronous methods on tens of thousands of accelerators. As a result, LongCat-Flash-Thinking achieves state-of-the-art performance among open-source models on a suite of complex reasoning tasks. The model exhibits exceptional efficiency in agentic reasoning, reducing average token consumption by 64.5% (from 19, 653 to 6, 965) on AIME-25, without degrading task accuracy. We release LongCat-Flash-Thinking to promote further advances in reasoning systems and agentic AI research.
Graph Learning
Xia, Feng, Peng, Ciyuan, Ren, Jing, Febrinanto, Falih Gozi, Luo, Renqiang, Saikrishna, Vidya, Yu, Shuo, Kong, Xiangjie
Graph learning has rapidly evolved into a critical subfield of machine learning and artificial intelligence (AI). Its development began with early graph-theoretic methods, gaining significant momentum with the advent of graph neural networks (GNNs). Over the past decade, progress in scalable architectures, dynamic graph modeling, multimodal learning, generative AI, explainable AI (XAI), and responsible AI has broadened the applicability of graph learning to various challenging environments. Graph learning is significant due to its ability to model complex, non-Euclidean relationships that traditional machine learning struggles to capture, thus better supporting real-world applications ranging from drug discovery and fraud detection to recommender systems and scientific reasoning. However, challenges like scalability, generalization, heterogeneity, interpretability, and trustworthiness must be addressed to unlock its full potential. This survey provides a comprehensive introduction to graph learning, focusing on key dimensions including scalable, temporal, multimodal, generative, explainable, and responsible graph learning. We review state-of-the-art techniques for efficiently handling large-scale graphs, capturing dynamic temporal dependencies, integrating heterogeneous data modalities, generating novel graph samples, and enhancing interpretability to foster trust and transparency. We also explore ethical considerations, such as privacy and fairness, to ensure responsible deployment of graph learning models. Additionally, we identify and discuss emerging topics, highlighting recent integration of graph learning and other AI paradigms and offering insights into future directions. This survey serves as a valuable resource for researchers and practitioners seeking to navigate the rapidly evolving landscape of graph learning.
Optimizing Anytime Reasoning via Budget Relative Policy Optimization
Qi, Penghui, Liu, Zichen, Pang, Tianyu, Du, Chao, Lee, Wee Sun, Lin, Min
Scaling test-time compute is crucial for enhancing the reasoning capabilities of large language models (LLMs). Existing approaches typically employ reinforcement learning (RL) to maximize a verifiable reward obtained at the end of reasoning traces. However, such methods optimize only the final performance under a large and fixed token budget, which hinders efficiency in both training and deployment. In this work, we present a novel framework, AnytimeReasoner, to optimize anytime reasoning performance, which aims to improve token efficiency and the flexibility of reasoning under varying token budget constraints. To achieve this, we truncate the complete thinking process to fit within sampled token budgets from a prior distribution, compelling the model to summarize the optimal answer for each truncated thinking for verification. This introduces verifiable dense rewards into the reasoning process, facilitating more effective credit assignment in RL optimization. We then optimize the thinking and summary policies in a decoupled manner to maximize the cumulative reward. Additionally, we introduce a novel variance reduction technique, Budget Relative Policy Optimization (BRPO), to enhance the robustness and efficiency of the learning process when reinforcing the thinking policy. Empirical results in mathematical reasoning tasks demonstrate that our method consistently outperforms GRPO across all thinking budgets under various prior distributions, enhancing both training and token efficiency.
TimeSearch-R: Adaptive Temporal Search for Long-Form Video Understanding via Self-Verification Reinforcement Learning
Pan, Junwen, Zhang, Qizhe, Zhang, Rui, Lu, Ming, Wan, Xin, Zhang, Yuan, Liu, Chang, She, Qi
Temporal search aims to identify a minimal set of relevant frames from tens of thousands based on a given query, serving as a foundation for accurate long-form video understanding. Existing works attempt to progressively narrow the search space. However, these approaches typically rely on a hand-crafted search process, lacking end-to-end optimization for learning optimal search strategies. In this paper, we propose TimeSearch-R, which reformulates temporal search as interleaved text-video thinking, seamlessly integrating searching video clips into the reasoning process through reinforcement learning (RL). However, applying RL training methods, such as Group Relative Policy Optimization (GRPO), to video reasoning can result in unsupervised intermediate search decisions. This leads to insufficient exploration of the video content and inconsistent logical reasoning. To address these issues, we introduce GRPO with Completeness Self-Verification (GRPO-CSV), which gathers searched video frames from the interleaved reasoning process and utilizes the same policy model to verify the adequacy of searched frames, thereby improving the completeness of video reasoning. Additionally, we construct datasets specifically designed for the SFT cold-start and RL training of GRPO-CSV, filtering out samples with weak temporal dependencies to enhance task difficulty and improve temporal search capabilities. Extensive experiments demonstrate that TimeSearch-R achieves significant improvements on temporal search benchmarks such as Haystack-LVBench and Haystack-Ego4D, as well as long-form video understanding benchmarks like VideoMME and MLVU. Notably, TimeSearch-R establishes a new state-of-the-art on LongVideoBench with 4.1% improvement over the base model Qwen2.5-VL and 2.0% over the advanced video reasoning model Video-R1. Our code is available at https://github.com/Time-Search/TimeSearch-R.
iFlyBot-VLM Technical Report
Nie, Xin, Cheng, Zhiyuan, Zhang, Yuan, Ji, Chao, Wu, Jiajia, Zhang, Yuhan, Pan, Jia
We introduce iFlyBot-VLM, a general-purpose Vision-Language Model (VLM) used to improve the domain of Embodied Intelligence. The central objective of iFlyBot-VLM is to bridge the cross-modal semantic gap between high-dimensional environmental perception and low-level robotic motion control. To this end, the model abstracts complex visual and spatial information into a body-agnostic and transferable Operational Language, thereby enabling seamless perception-action closed-loop coordination across diverse robotic platforms. The architecture of iFlyBot-VLM is systematically designed to realize four key functional capabilities essential for embodied intelligence: 1) Spatial Understanding and Metric Reasoning; 2) Interactive Target Grounding; 3) Action Abstraction and Control Parameter Generation; 4) Task Planning and Skill Sequencing. We envision iFlyBot-VLM as a scalable and generalizable foundation model for embodied AI, facilitating the progression from specialized task-oriented systems toward generalist, cognitively capable agents. We conducted evaluations on 10 current mainstream embodied intelligence-related VLM benchmark datasets, such as Blink and Where2Place, and achieved optimal performance while preserving the model's general capabilities. We will publicly release both the training data and model weights to foster further research and development in the field of Embodied Intelligence.
You Need Reasoning to Learn Reasoning: The Limitations of Label-Free RL in Weak Base Models
Roy, Shuvendu, Hajimirsadeghi, Hossein, Zhai, Mengyao, Samei, Golnoosh
Recent advances in large language models have demonstrated the promise of unsupervised reinforcement learning (RL) methods for enhancing reasoning capabilities without external supervision. However, the generalizability of these label-free RL approaches to smaller base models with limited reasoning capabilities remains unexplored. In this work, we systematically investigate the performance of label-free RL methods across different model sizes and reasoning strengths, from 0.5B to 7B parameters. Our empirical analysis reveals critical limitations: label-free RL is highly dependent on the base model's pre-existing reasoning capability, with performance often degrading below baseline levels for weaker models. We find that smaller models fail to generate sufficiently long or diverse chain-of-thought reasoning to enable effective self-reflection, and that training data difficulty plays a crucial role in determining success. To address these challenges, we propose a simple yet effective method for label-free RL that utilizes curriculum learning to progressively introduce harder problems during training and mask no-majority rollouts during training. Additionally, we introduce a data curation pipeline to generate samples with predefined difficulty. Our approach demonstrates consistent improvements across all model sizes and reasoning capabilities, providing a path toward more robust unsupervised RL that can bootstrap reasoning abilities in resource-constrained models. We make our code available at https://github.com/BorealisAI/CuMa
Learning to reason about rare diseases through retrieval-augmented agents
Kim, Ha Young, Li, Jun, Solana, Ana Beatriz, Pirkl, Carolin M., Wiestler, Benedikt, Schnabel, Julia A., Bercea, Cosmin I.
Rare diseases represent the long tail of medical imaging, where AI models often fail due to the scarcity of representative training data. In clinical workflows, radiologists frequently consult case reports and literature when confronted with unfamiliar findings. Following this line of reasoning, we introduce RADAR, Retrieval Augmented Diagnostic Reasoning Agents, an agentic system for rare disease detection in brain MRI. Our approach uses AI agents with access to external medical knowledge by embedding both case reports and literature using sentence transformers and indexing them with FAISS to enable efficient similarity search. The agent retrieves clinically relevant evidence to guide diagnostic decision making on unseen diseases, without the need of additional training. Designed as a model-agnostic reasoning module, RADAR can be seamlessly integrated with diverse large language models, consistently improving their rare pathology recognition and interpretability. On the NOVA dataset comprising 280 distinct rare diseases, RADAR achieves up to a 10.2% performance gain, with the strongest improvements observed for open source models such as DeepSeek. Beyond accuracy, the retrieved examples provide interpretable, literature grounded explanations, highlighting retrieval-augmented reasoning as a powerful paradigm for low-prevalence conditions in medical imaging.
Every Activation Boosted: Scaling General Reasoner to 1 Trillion Open Language Foundation
Ling Team, null, Li, Ang, Liu, Ben, Hu, Binbin, Li, Bing, Zeng, Bingwei, Ye, Borui, Tang, Caizhi, Tian, Changxin, Huang, Chao, Zhang, Chao, Qian, Chen, Ju, Chenchen, Li, Chenchen, Tang, Chengfu, Fu, Chilin, Ren, Chunshao, Wu, Chunwei, Zhang, Cong, Peng, Cunyin, Xu, Dafeng, Wang, Daixin, Zhang, Dalong, Jin, Dingnan, Zhu, Dingyuan, Hu, Dongke, Zhao, Fangzheng, Wu, Feifan, Zhu, Feng, Wang, Gangshan, Zhang, Haitao, Zhao, Hailin, Zhang, Hanxiao, Wang, Hanzi, Qian, Hao, Yu, Haoyi, Zhang, Heng, Zhang, Hongliang, Luan, Hongzhi, Dong, Huirong, Li, Huizhong, Li, Jia, Liu, Jia, Zhu, Jialong, Sha, Jian, Wei, Jianping, Yang, Jiaolong, Ma, Jieyue, Wu, Jiewei, Huang, Jinjing, Tian, Jingyun, Zhang, Jingyuan, Sun, Jinquan, Tu, Juanhui, Liu, Jun, Xu, Jun, Zhou, Jun, Ou, Junjie, Fang, Junpeng, Zhang, Kaihong, Hu, Kaiqin, Shi, Ke, Tang, Kun, Chen, Kunlong, Mei, Lanyin, Liang, Lei, Xu, Lei, Zhang, Libo, Ju, Lin, Yuan, Lin, Zhong, Ling, Ma, Lintao, Liu, Lu, Yu, Lu, Cai, Lun, Zhu, Meiqi, Li, Mengying, Chen, Min, Xue, Minghao, Cai, Minghong, Yin, Mingming, Jiang, Peijie, Zhao, Peilong, Liu, Pingping, Zhao, Qian, Cui, Qing, Huang, Qingxiang, Yang, Qingyuan, Yu, Quankun, Wei, Shaowei, Lian, Shijie, Zheng, Shoujian, Song, Shun, Zhang, Shungen, Zhang, Shuo, Li, Siyuan, Liu, Song, Guo, Ting, Zhao, Tong, Gu, Wanli, Wu, Weichang, Han, Weiguang, Fang, Wenjing, Wang, Wubin, Shu, Xiang, Shi, Xiao, Lan, Xiaoshun, Zhang, Xiaolu, Sun, Xiaqing, Zhao, Xin, Lu, Xingyu, Xu, Xiong, Wang, Xudong, Wang, Xudong, Yang, Xuemin, Yang, Yajie, Xiang, Yang, Li, Yanzhe, Zhang, Yi, Wang, Yilong, Li, Yingxue, Guo, Yongzhen, Fu, Yuzhuo, Wang, Yuanyuan, Yang, Yue, Yu, Yue, Deng, Yufeng, Zhang, Yun, Yu, Yunfei, Zhang, Yuqi, He, Yuxiao, Gui, Zengke, Huan, Zhaoxin, Wang, Zhaoyang, Zhu, Zhibo, Wang, Zhihao, Zhang, Zhiqiang, Wang, Zhoufei, Zeng, Zihang, Liu, Ziqi, Xuan, Zitao, Tang, Zuoli
We introduce Ling 2.0, a series reasoning-oriented language foundation built upon the principle that every activation boosts reasoning capability. Designed to scale from tens of billions to one trillion parameters under a unified Mixture-of-Experts (MoE) paradigm, Ling 2.0 emphasizes high sparsity, cross-scale consistency, and efficiency guided by empirical scaling laws. The series includes three non-thinking (instruct) models - Ling-mini-2.0, Ling-flash-2.0, and Ling-1T - ranging from 16B to 1T total parameters and achieving up to 7-fold active-compute efficiency compared with dense counterparts. Ling 2.0 integrates coordinated innovations across model architecture, pre-training, post-training, and infrastructure: a high-sparsity MoE with MTP for efficient reasoning, reasoning-oriented data and mid-training CoT activation, reinforcement-based fine-tuning (DFT, Evo-CoT), and full-scale FP8 training with fine-grained heterogeneous pipelines. At the trillion scale, Ling-1T establishes a new Pareto frontier of reasoning accuracy versus computational efficiency, demonstrating that sparse activation, when properly aligned with reasoning objectives, enables scalable and efficient intelligence. Collectively, Ling 2.0 provides a coherent, open, and efficient foundation for advancing future reasoning and thinking models, including the Ring series built upon the same base.