用推理计算生成无监督信号,让模型在无真实答案时也能训练。
Compute as Teacher: Turning Inference Compute Into Reference-Free Supervision
- 通过并行推理生成伪参考答案,作为强化学习的监督信号。
- 在HealthBench上仅用1/9测试计算量,效果媲美或超过人工聚合。
- 适用于医疗等无法验证的领域,也兼容可验证任务,适配性强。
当后训练阶段缺乏真实标签时,学习信号从何而来?我们发现推理计算本身可作为监督信号。通过生成并行推理轨迹并转化为伪参考答案,模型可在无需人工标注的情况下学习——尤其在医疗建议等无法程序化校验的领域中具有重要意义。我们提出「计算即教师」(Compute as Teacher, CaT)框架,将推理时的并行计算转化为强化学习的监督信号。该框架包含两部分:(1)参考估计,将多个推理轨迹聚合为伪参考答案;(2)奖励生成,将伪参考转化为强化学习奖励。在(1)中,我们提出一种称为“合成”的简单方法,但框架支持任意聚合器;在(2)中,我们引入自生成评分标准,针对不可验证领域设计二元可审计判据,由大语言模型评分。在HealthBench上,使用CaT训练的模型达到与推理时聚合相当甚至更优的效果,同时测试计算量减少9倍。此外,其性能可媲美专家医生标注,相较初始策略最高提升30%。该框架还可扩展至可验证奖励场景,在MATH-500上的测试时强化学习表现匹配最优基线,展现出跨领域“即插即用”的通用性。
原文摘要 · Abstract (English)
Where do learning signals come from when there is no ground truth in post-training? We show that inference compute itself can serve as supervision. By generating parallel rollouts and converting them into reference estimates, models can learn without human labels-critically, even in non-verifiable domains like healthcare guidance where no programmatic checker exists. We call this framework Compute as Teacher (CaT) and it turns inference-time compute from parallel rollouts into supervision for RL training. The framework has two components: (1) reference estimation which aggregates rollouts into a pseudo-reference answer, and (2) reward derivation which converts that pseudo-reference into RL rewards. For (1), we explore a simple method we call synthesis, but the framework admits any aggregator. For (2), we introduce self-proposed rubrics for non-verifiable domains. These are binary, auditable criteria generated from the pseudo-reference and scored by an LLM judge. On HealthBench, models trained with CaT match or exceed inference-time aggregation quality while using 9x less test-time compute. Here, CaT also competes with learning from expert physician annotations, yielding up to +30% relative improvement over the initial policy. The framework extends naturally to verifiable rewards, matching the best existing baselines on MATH-500 in test-time RL and demonstrating 'drop-in' versatility across both types of domains.
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