TTRL: Test-Time Reinforcement Learning
Authors: name: Yuxin Zuo, name: Kaiyan Zhang, name: Shang Qu, name: Li Sheng, name: Xuekai Zhu, name: Biqing Qi, name: Youbang Sun, name: Ganqu Cui, name: Ning Ding, name: Bowen Zhou

This paper investigates Reinforcement Learning (RL) on data without explicit
labels for reasoning tasks in Large Language Models (LLMs). The core challenge
of the problem is reward estimation during inference while not having access to
ground-truth information. While this setting appears elusive, we find that
common practices in Test-Time Scaling (TTS), such as majority voting, yield
surprisingly effective rewards suitable for driving RL training. In this work,
we introduce Test-Time Reinforcement Learning (TTRL), a novel method for
training LLMs using RL on unlabeled data. TTRL enables self-evolution of LLMs
by utilizing the priors in the pre-trained models. Our experiments demonstrate
that TTRL consistently improves performance across a variety of tasks and
models. Notably, TTRL boosts the pass@1 performance of Qwen-2.5-Math-7B by
approximately 159% on the AIME 2024 with only unlabeled test data. Furthermore,
although TTRL is only supervised by the Maj@N metric, TTRL has demonstrated
performance to consistently surpass the upper limit of the initial model, and
approach the performance of models trained directly on test data with
ground-truth labels. Our experimental findings validate the general
effectiveness of TTRL across various tasks, and highlight TTRL's potential for
broader tasks and domains. GitHub: https://github.com/PRIME-RL/TTRL