arXiv:2607.01179cs.LGcs.CL2026-07被引 1

用相关采样提升大模型推理效率,减少冗余计算。

QuasiMoTTo: Quasi-Monte Carlo Test-Time Scaling

  • 用准蒙特卡洛方法生成相关但精确的采样,替代独立采样。
  • 在四个推理基准上,样本量减少25%-47%仍达相同准确率。
  • 适合需要高效推理或强化学习的场景,尤其关注算力利用率。

通过并行生成多个尝试来扩展推理计算,是提升语言模型能力的有效手段,但默认的独立采样会浪费算力于重复解。这种浪费看似不可避免,因为独立性便于扩展。然而,这并非本质限制:存在丰富的采样器设计空间,可在完全并行下生成相关且精确的样本。本文探索该空间,提出QuasiMoTTo,将相关采样作为i.i.d.采样的即插即用替代。其核心是将自回归采样重参数化为逆CDF采样,并使用准蒙特卡洛(QMC)生成均匀分布;由于QMC更均匀地分布随机数,输出空间覆盖更高效,冗余显著降低。尽管批次内样本相关,但每个样本边际分布仍符合语言模型,可用于策略梯度训练。我们开发了无偏自助估计器以评估相关采样,因其依赖性破坏标准pass@k估计。在四个推理基准上,QuasiMoTTo以25%-47%更少样本达到i.i.d.的pass@k准确率。惊人的是,它常达到任意边际保持采样器的pass@k上限。在策略梯度强化学习(GRPO)中,其性能与i.i.d.相当,但仅需一半训练步数。这些增益源于更高覆盖率,带来更强的学习信号。

原文摘要 · Abstract (English)

Scaling inference compute, by generating many parallel attempts per problem, is a costly but reliable lever for improving language model capabilities. By default these attempts are generated independently, wasting inference compute on redundant solutions. This waste seems unavoidable. After all, independence is what makes parallel sampling trivial to scale. However, this tradeoff is not fundamental: there is a rich design space of samplers that generate correlated but exact samples entirely in parallel. We explore this design space as an avenue for improving sample efficiency in scaling inference compute and reinforcement learning (RL). Concretely, we introduce QuasiMoTTo, which uses correlated samples as a drop-in replacement for i.i.d. samples. To generate these samples, QuasiMoTTo uses a reparameterization of autoregressive sampling as inverse-CDF sampling and draws the underlying uniforms with quasi-Monte Carlo (QMC); because QMC spreads the uniforms out more evenly than i.i.d., the resulting samples cover the output space with far less redundancy. Even though the batch is correlated, each sample is marginally distributed according to the language model, so we can use the batch for policy-gradient training. Our empirical analysis focuses on understanding how efficiently QuasiMoTTo can turn compute into performance. To evaluate correlated samplers, whose dependence breaks standard pass@k estimators, we first develop an unbiased bootstrap estimator. Across four reasoning benchmarks, QuasiMoTTo matches i.i.d. pass@k accuracy with 25-47% fewer samples. Strikingly, QuasiMoTTo often saturates an upper bound on pass@k that holds for any marginal-preserving sampler. We also apply QuasiMoTTo to policy-gradient RL (GRPO) where it matches i.i.d. performance with 50% fewer training steps. These gains come from higher coverage, which yields a stronger learning signal per batch.

推理优化采样效率强化学习

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