打破生成模型的伪二分法,强调推理阶段设计优先。
Ideas in Inference-time Scaling can Benefit Generative Pre-training Algorithms

- 以推理过程为核心重构生成模型框架,区分序列扩展与状态精炼。
- 揭示DDIM采样器在目标时间上的局限性,验证推理效率关键作用。
- 适合关注高效推理与生成模型架构设计的研究者。
生成式预训练常被误认为离散信号的自回归模型与连续信号的扩散模型之间的对立。我们指出这种对立是错误的,因为它混淆了模型族、数据表示、训练目标和推理过程。自回归是一种通过归一化条件采样扩展序列的推理方式,而扩散是一种反复修正已有状态的精炼过程。更本质的对比应是:基于交叉熵学习离散标记与基于扩散式目标学习连续标记,以及相应的采样推理算法。因此,算法进展应优先关注推理阶段的效率,涵盖序列扩展与状态精炼两个维度。我们主张先设计推理过程,再确定训练目标,因为训练方法无法弥补推理映射中遗漏必要变量或施加错误因子分解的问题。本文通过分析DDIM类采样器的目标时间限制、多标记预测的联合分布限制,以及近期流映射与少步蒸馏方法直接参数化长程推理动作,验证了该原则。
原文摘要 · Abstract (English)
Generative pre-training is often framed through a false dichotomy between autoregressive models for discrete signals and diffusion models for continuous signals. We argue that the dichotomy is false because it conflates model family, data representation, training objective, and inference procedure. Autoregression is an inference procedure that expands a sequence through normalized conditional draws, while diffusion is a refinement procedure that repeatedly revises an existing state. The more useful contrast is therefore not autoregressive versus diffusion, but discrete tokens learned with cross-entropy versus continuous tokens learned with diffusion-style objectives, together with the inference algorithms used to sample from them. From this perspective, algorithmic progress should prioritize inference-time efficiency along two axes: sequence expansion and state refinement. We advocate designing the inference procedure before the training objective, because a training method cannot compensate for an inference map that omits necessary arguments or imposes an incorrect factorization. We illustrate this principle through a target-time limitation of DDIM-style samplers, a joint-distribution limitation of multi-token prediction, and recent flow-map and few-step distillation methods that directly parameterize long-range inference moves.
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