论文标题

对比条件神经过程

Contrastive Conditional Neural Processes

论文作者

Ye, Zesheng, Yao, Lina

论文摘要

有条件的神经过程〜(CNP)桥接神经网络,具有概率推断,以对元学习环境下随机过程的近似功能进行概率。给定一批非 - {\ it I.I.D}函数实例化,CNP被共同优化,以在生成重建管道内的实体观察预测和跨构成元代表性适应。当功能观测值量表与高维和嘈杂的空间时,将这两个目标绑在一起可能会有挑战。取而代之的是,噪声对比的估计可能能够通过学习分布匹配的目标来打击这种生成模型的这种固有限制,从而提供更强大的表示。鉴于此,我们提议通过1)将预测与编码的地面真相观察对齐,以及2)将元代表的适应性与生成重建相结合。具体而言,在层次上建立了两个辅助对比分支,即实现时间对比度学习〜({\ tt tt tcl})和交叉启动功能对比度学习〜({\ tt fcl}),以促进局部预测和全球功能一致性。我们从经验上表明,{\ tt tcl}捕获了观测值的高级抽象,而{\ tt fcl}有助于识别潜在的功能,这又提供了更有效的表示。在评估功能分布重建和参数识别跨1D,2D和高维时序列时,我们的模型优于其他CNP变体。

Conditional Neural Processes~(CNPs) bridge neural networks with probabilistic inference to approximate functions of Stochastic Processes under meta-learning settings. Given a batch of non-{\it i.i.d} function instantiations, CNPs are jointly optimized for in-instantiation observation prediction and cross-instantiation meta-representation adaptation within a generative reconstruction pipeline. There can be a challenge in tying together such two targets when the distribution of function observations scales to high-dimensional and noisy spaces. Instead, noise contrastive estimation might be able to provide more robust representations by learning distributional matching objectives to combat such inherent limitation of generative models. In light of this, we propose to equip CNPs by 1) aligning prediction with encoded ground-truth observation, and 2) decoupling meta-representation adaptation from generative reconstruction. Specifically, two auxiliary contrastive branches are set up hierarchically, namely in-instantiation temporal contrastive learning~({\tt TCL}) and cross-instantiation function contrastive learning~({\tt FCL}), to facilitate local predictive alignment and global function consistency, respectively. We empirically show that {\tt TCL} captures high-level abstraction of observations, whereas {\tt FCL} helps identify underlying functions, which in turn provides more efficient representations. Our model outperforms other CNPs variants when evaluating function distribution reconstruction and parameter identification across 1D, 2D and high-dimensional time-series.

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