Reinforcement Learning

InftyThink+: Effective and Efficient Infinite-Horizon Reasoning via Reinforcement Learning

YYuchen YanLLiang JiangJJin JiangSShuaicheng LiZZujie WenZZhiqiang ZhangJJun ZhouJJian ShaoYYueting ZhuangYYongliang Shen
Published
February 6, 2026
Authors
10
Word Count
12,608
Code
Includes code

Enhanced reasoning model efficiency with InftyThink+.

Abstract

Large reasoning models achieve strong performance by scaling inference-time chain-of-thought, but this paradigm suffers from quadratic cost, context length limits, and degraded reasoning due to lost-in-the-middle effects. Iterative reasoning mitigates these issues by periodically summarizing intermediate thoughts, yet existing methods rely on supervised learning or fixed heuristics and fail to optimize when to summarize, what to preserve, and how to resume reasoning. We propose InftyThink+, an end-to-end reinforcement learning framework that optimizes the entire iterative reasoning trajectory, building on model-controlled iteration boundaries and explicit summarization. InftyThink+ adopts a two-stage training scheme with supervised cold-start followed by trajectory-level reinforcement learning, enabling the model to learn strategic summarization and continuation decisions. Experiments on DeepSeek-R1-Distill-Qwen-1.5B show that InftyThink+ improves accuracy by 21% on AIME24 and outperforms conventional long chain-of-thought reinforcement learning by a clear margin, while also generalizing better to out-of-distribution benchmarks. Moreover, InftyThink+ significantly reduces inference latency and accelerates reinforcement learning training, demonstrating improved reasoning efficiency alongside stronger performance.

Key Takeaways

  • 1

    InftyThink+ optimizes iterative reasoning via reinforcement learning.

  • 2

    Significantly improves accuracy and reduces inference latency.

  • 3

    Addresses key challenges in scaling large reasoning models.

Limitations

  • Lacks explicit control over summary organization and fidelity.

  • Relies on natural language summaries with inherent constraints.

Keywords

chain-of-thoughtiterative reasoningreinforcement learningtrajectory-level reinforcement learningsummarizationreasoning efficiencyinference latency

More in Reinforcement Learning

View all
InftyThink+: Effective and Efficient Infinite-Horizon Reasoning via Reinforcement Learning | Paperchime