发现大模型多试几次后成功率呈幂律增长,原因在于少数难题拖累整体表现。
How Do Large Language Monkeys Get Their Power (Laws)?
- 用重尾分布解释为何单题指数提升却整体呈现幂律趋势
- 实验证明多数问题成功概率随尝试次数指数下降,但极难任务影响全局
- 可大幅减少推理计算量预测模型性能,适合评估与优化大模型
近期研究在数学求解、证明助手编程及多模态越狱任务中发现:当(多模态)语言模型对每项任务进行多次尝试(只要一次成功即算成功)时,平均成功率的负对数随尝试次数呈幂律变化。本文揭示一个矛盾:简单数学推导预测每道题的失败率应随尝试次数指数下降,实验也证实了这一点。然而,聚合层面却呈现多项式缩放。我们解答此谜题:若单次尝试成功率的分布具有重尾特征——即少数任务的成功概率极低——这些极难任务会共同扭曲整体趋势,使其表现为幂律,即使每个问题自身仍为指数级提升。我们进一步验证该分布视角可解释以往偏离幂律的现象,并提供一种预测幂律指数的方法,相对误差降低一个数量级,或等效减少2-4个数量级的推理计算开销。本工作深化了对神经语言模型在增加推理计算下的性能提升机制的理解,推动了可预测的(多模态)语言模型评估体系发展。
原文摘要 · Abstract (English)
Recent research across mathematical problem solving, proof assistant programming and multimodal jailbreaking documents a striking finding: when (multimodal) language model tackle a suite of tasks with multiple attempts per task -- succeeding if any attempt is correct -- then the negative log of the average success rate scales a power law in the number of attempts. In this work, we identify an apparent puzzle: a simple mathematical calculation predicts that on each problem, the failure rate should fall exponentially with the number of attempts. We confirm this prediction empirically, raising a question: from where does aggregate polynomial scaling emerge? We then answer this question by demonstrating per-problem exponential scaling can be made consistent with aggregate polynomial scaling if the distribution of single-attempt success probabilities is heavy tailed such that a small fraction of tasks with extremely low success probabilities collectively warp the aggregate success trend into a power law - even as each problem scales exponentially on its own. We further demonstrate that this distributional perspective explains previously observed deviations from power law scaling, and provides a simple method for forecasting the power law exponent with an order of magnitude lower relative error, or equivalently, ${\sim}2-4$ orders of magnitude less inference compute. Overall, our work contributes to a better understanding of how neural language model performance improves with scaling inference compute and the development of scaling-predictable evaluations of (multimodal) language models.
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