mlsanityData to 14 Oct 2026

Thinking-Free Policy Initialization Makes Distilled Reasoning Models More Effective and Efficient Reasoners

arXiv 2509.26226 ↗First posted 30 Sep 2025cs.LG cs.CLcited by 5

On the map: LLM reasoning → Reinforcement learning for reasoning

also in 1 more
Abstract (arXiv)

Reinforcement Learning with Verifiable Reward (RLVR) effectively solves complex tasks but demands extremely long context lengths during training, leading to substantial computational costs. While multi-stage training can partially mitigate this, starting with overly short contexts often causes irreversible performance degradation, ultimately failing to reduce overall training compute significantly. In this paper, we introduce Thinking-Free Policy Initialization (TFPI), a simple yet effective adaptation to RLVR that bridges long Chain-of-Thought (CoT) distillation and standard RLVR. TFPI employs a simple ThinkingFree operation, explicitly discarding the thinking content via a direct </think> append, to reduce token usage during inference. Training with ThinkingFree-adapted inputs improves performance and lowers token consumption, even in the original slow-thinking mode. Extensive experiments across various benchmarks have shown that TFPI accelerates RL convergence, achieves a higher performance ceiling, and yields more token-efficient reasoning models without specialized rewards or complex training designs. With TFPI only, we train a 4B model to reach 89.0% accuracy on AIME24 and 65.5% on LiveCodeBench using less than 4K H20 hours.

Key facts. Cited by 5 papers in the map (data through 14 Oct 2026). Placed in Reinforcement learning for reasoning, one of 17 directions in LLM reasoning. Builds on 64 of its 74 references that are in the map. First posted on arXiv 30 Sep 2025.

Builds on

64 of 74 references.

Closest ancestors · 11

Same direction, newest first

  1. 2025Sample More to Think Less: Group Filtered Policy Optimization for Concise Reasoning13 Aug
  2. 2025OctoThinker: Mid-training Incentivizes Reinforcement Learning Scaling25 Jun
  3. 2025Critique-GRPO: Advancing LLM Reasoning with Natural Language and Numerical Feedback3 Jun
  4. 2025Beyond the 80/20 Rule: High-Entropy Minority Tokens Drive Effective Reinforcement Learning for LLM Reasoning2 Jun
  5. 2025Understanding R1-Zero-Like Training: A Critical Perspective26 Mar
  6. 2025SimpleRL-Zoo: Investigating and Taming Zero Reinforcement Learning for Open Base Models in the Wild24 Mar
  7. 2025DAPO: An Open-Source LLM Reinforcement Learning System at Scale18 Mar
  8. 2025Training Language Models to Reason Efficiently6 Feb
  9. 2025DeepSeek-R1: Incentivizing Reasoning Capability in LLMs via Reinforcement Learning22 Jan
  10. 2025Kimi k1.5: Scaling Reinforcement Learning with LLMs22 Jan
  11. 2017Proximal Policy Optimization Algorithms20 Jul

Other references · 53

  1. 2024DeepSeekMath: Pushing the Limits of Mathematical Reasoning in Open Language Modelscited by 9,379
  2. 2025Qwen3 Technical Reportcited by 8,820
  3. 2024HybridFlow: A Flexible and Efficient RLHF Frameworkcited by 2,057
  4. 2024LiveCodeBench: Holistic and Contamination Free Evaluation of Large Language Models for Codecited by 2,004
  5. 2025Search-R1: Training LLMs to Reason and Leverage Search Engines with Reinforcement Learningcited by 1,444
  6. 2025s1: Simple test-time scalingcited by 1,341
  7. 2024OpenAI o1 System Cardcited by 1,244
  8. 2023Instruction-Following Evaluation for Large Language Modelscited by 1,228
  9. 2024Qwen2.5-Math Technical Report: Toward Mathematical Expert Model via Self-Improvementcited by 1,090
  10. 2025Group Sequence Policy Optimizationcited by 835
  11. 2023MetaMath: Bootstrap Your Own Mathematical Questions for Large Language Modelscited by 735
  12. 2024Do NOT Think That Much for 2+3=? On the Overthinking of o1-Like LLMscited by 570
38 more
  1. 2025Kimi K2: Open Agentic Intelligencecited by 567
  2. 2025LIMO: Less is More for Reasoningcited by 498
  3. 2025Humanity's Last Examcited by 491
  4. 2025GLM-4.5: Agentic, Reasoning, and Coding (ARC) Foundation Modelscited by 467
  5. 2025Stop Overthinking: A Survey on Efficient Reasoning for Large Language Modelscited by 464
  6. 2025ReTool: Reinforcement Learning for Strategic Tool Use in LLMscited by 392
  7. 2025L1: Controlling How Long A Reasoning Model Thinks With Reinforcement Learningcited by 384
  8. 2025MM-Eureka: Exploring the Frontiers of Multimodal Reasoning with Rule-based Reinforcement Learningcited by 303
  9. 2025O1-Pruner: Length-Harmonizing Fine-Tuning for O1-Like Reasoning Pruningcited by 279
  10. 2025Dynamic Early Exit in Reasoning Modelscited by 219
  11. 2025Deep Think with Confidencecited by 205
  12. 2025CoT-Valve: Length-Compressible Chain-of-Thought Tuningcited by 169
  13. 2025ToRL: Scaling Tool-Integrated RLcited by 169
  14. 2025Skywork Open Reasoner 1 Technical Reportcited by 165
  15. 2025Seed1.5-Thinking: Advancing Superb Reasoning Models with Reinforcement Learningcited by 161
  16. 2025AdaptThink: Reasoning Models Can Learn When to Thinkcited by 147
  17. 2025Thinkless: LLM Learns When to Thinkcited by 113
  18. 2025Self-Training Elicits Concise Reasoning in Large Language Modelscited by 99
  19. 2025Perception-Aware Policy Optimization for Multimodal Reasoningcited by 99
  20. 2023Levels of AGI for Operationalizing Progress on the Path to AGIcited by 96
  21. 2024DART-Math: Difficulty-Aware Rejection Tuning for Mathematical Problem-Solvingcited by 95
  22. 2025AdaCoT: Pareto-Optimal Adaptive Chain-of-Thought Triggering via Reinforcement Learningcited by 87
  23. 2025Learn to Reason Efficiently with Adaptive Length-based Reward Shapingcited by 75
  24. 2025SEAL: Steerable Reasoning Calibration of Large Language Models for Freecited by 68
  25. 2025Think Only When You Need with Large Hybrid-Reasoning Modelscited by 66
  26. 2025Learning When to Think: Shaping Adaptive Reasoning in R1-Style Models via Multi-Stage RLcited by 62
  27. 2025e3: Learning to Explore Enables Extrapolation of Test-Time Compute for LLMscited by 59
  28. 2025UGPhysics: A Comprehensive Benchmark for Undergraduate Physics Reasoning with Large Language Modelscited by 48
  29. 2025SelfBudgeter: Adaptive Token Allocation for Efficient LLM Reasoningcited by 48
  30. 2025Perception-R1: Advancing Multimodal Reasoning Capabilities of MLLMs via Visual Perception Rewardcited by 45
  31. 2025Between Circuits and Chomsky: Pre-pretraining on Formal Languages Imparts Linguistic Biasescited by 37
  32. 2025BudgetThinker: Empowering Budget-aware LLM Reasoning with Control Tokenscited by 29
  33. 2025When to Continue Thinking: Adaptive Thinking Mode Switching for Efficient Reasoningcited by 26
  34. 2025VeriThinker: Learning to Verify Makes Reasoning Model Efficientcited by 24
  35. 2024Can LLMs Solve longer Math Word Problems Better?cited by 22
  36. 2025Train Long, Think Short: Curriculum Learning for Efficient Reasoningcited by 20
  37. 2025Incentivizing LLMs to Self-Verify Their Answerscited by 17
  38. 2025UGMathBench: A Diverse and Dynamic Benchmark for Undergraduate-Level Mathematical Reasoning with Large Language Modelscited by 13

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Cited by year (2026 to 14 Oct)

Citing papers per year: 2025: 1; 2026: 4.

5 papers.

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Close in wording, no citation either way

  1. 2025The Markovian Thinker: Architecture-Agnostic Linear Scaling of Reasoning
  2. 2026Resource-Efficient Reinforcement for Reasoning Large Language Models via Dynamic One-Shot Policy Refinement
  3. 2026OPSD Compresses What RLVR Teaches: A Post-RL Compaction Stage for Reasoning Models
  4. 2025Reinforcement Learning with Verifiable Rewards Implicitly Incentivizes Correct Reasoning in Base LLMs
  5. 2026It Takes 8 Tokens: Weak-to-Strong Off-Policy RL via Auxiliary Branches
  6. 2025RLP: Reinforcement as a Pretraining Objective
  7. 2025ThinkPrune: Pruning Long Chain-of-Thought of LLMs via Reinforcement Learning
  8. 2026SARL: Label-Free Reinforcement Learning by Rewarding Reasoning Topology