arXiv:2605.26849cs.CL2026-05

根据题目难易动态分配计算资源,提升大模型推理效率。

Uncertainty-Aware Budget Allocation for Adaptive Test-Time Reasoning

  • 基于输出概率估计每题难度,无额外计算成本
  • 在六项测试中平均准确率提升最多3%,个别任务达5%
  • 适合资源有限的推理场景,无需额外模型或调用

多轮采样能提升语言模型推理效果,但均匀分配计算资源效率低:简单问题过度采样,难题仍采样不足。我们提出不确定性感知预算分配(UAB),一种凹型整数优化框架,基于每个问题的不确定性重新分配固定采样预算,且不增加额外推理开销。第一阶段,每个问题生成一次,其平均负对数似然(ANLL)直接从输出概率中提取,作为难度信号,同时该生成结果参与最终投票。第二阶段,剩余预算通过边际贪心算法分配,精确求解凹型覆盖最大化代理目标:不确定性高的问题获得更多采样,信心高的问题则减少追加样本。在涵盖1.5B至27B参数的六种开源与黑盒模型,以及数学、逻辑和偏好任务的五个推理基准上评估,UAB相比基线平均准确率最高提升3%,单个基准最高提升5%,在低资源环境下增益最显著,且无需辅助模型或额外大模型调用。代码已公开于https://github.com/manhitv/UAB。

原文摘要 · Abstract (English)

Sampling multiple responses improves language model reasoning, but uniform compute allocation is inefficient: easy questions are over-sampled while hard questions remain under-explored. We propose Uncertainty-Aware Budget Allocation (UAB), a concave integer optimization framework that reallocates a fixed sampling budget based on per-question uncertainty estimated at no additional inference cost. In Phase 1, every question receives one generation; its average negative log-likelihood (ANLL), extracted directly from output log-probabilities, serves as a difficulty signal while the generation contributes to the final vote. In Phase 2, the remaining budget is allocated by a marginal-greedy algorithm that solves a concave coverage-maximization surrogate exactly: uncertain questions receive more sampling budget while confident questions receive fewer additional samples. Evaluated on six open-weight and black-box models spanning 1.5B to 27B parameters and five reasoning benchmarks covering math, logic, and preference tasks, UAB outperforms baselines by up to +3% in average accuracy and up to +5% on individual benchmarks, with the largest gains in low-resource settings, requiring no auxiliary model or additional LLM call. Code is publicly available at https://github.com/manhitv/UAB.

推理优化采样策略预算分配

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