English

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

Machine Learning 2025-12-25 v2 Computation and Language

Abstract

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 **T**hinking-**F**ree **P**olicy **I**nitialization (**TFPI**), a simple yet effective adaptation to RLVR that bridges long Chain-of-Thought (CoT) distillation and standard RLVR. TFPI employs a simple *ThinkFree* operation, explicitly discarding the thinking content via a direct *</think>* append, to reduce token usage during inference. Training with *ThinkFree*-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.

Keywords

Cite

@article{arxiv.2509.26226,
  title  = {Thinking-Free Policy Initialization Makes Distilled Reasoning Models More Effective and Efficient Reasoners},
  author = {Xin Xu and Cliveb AI and Kai Yang and Tianhao Chen and Yang Wang and Saiyong Yang and Can Yang},
  journal= {arXiv preprint arXiv:2509.26226},
  year   = {2025}
}
R2 v1 2026-07-01T06:07:36.627Z