论文标题
用双曲线归一化流量的潜在变量建模
Latent Variable Modelling with Hyperbolic Normalizing Flows
论文作者
论文摘要
近似后分布的选择在随机变异推理(SVI)中起着核心作用。一种有效的解决方案是使用标准化流\ cut \ cut {定义在欧几里得空间上}来构建灵活的后验分布。但是,现有归一化流的一个关键限制是它们仅限于欧几里得空间,并且不适合用基本的层次结构对数据进行建模。为了解决这一基本限制,我们提出了将流量标准化到双曲线空间的首次扩展。我们首先使用在切线束上定义的耦合变换将标准化的流量提升到双曲线空间,称为切线耦合($ \ MATHCAL {TC} $)。我们进一步介绍包裹的拼双层耦合($ \ Mathcal {w} \ Mathbb {h} c $),这是一种完全可逆且可学习的转换,明确地利用了双曲线空间的几何结构,可用于表达后代,同时有效地从中有效地采样。我们证明了我们新颖的正常流量在双曲线VAE和欧几里得归一化流量上的功效。我们的方法在密度估计以及现实世界图数据的重建方面取得了改善,这些数据表现出层次结构。最后,我们表明我们的方法可用于使用双曲线潜在变量,通过分层数据为生成模型供电。
The choice of approximate posterior distributions plays a central role in stochastic variational inference (SVI). One effective solution is the use of normalizing flows \cut{defined on Euclidean spaces} to construct flexible posterior distributions. However, one key limitation of existing normalizing flows is that they are restricted to the Euclidean space and are ill-equipped to model data with an underlying hierarchical structure. To address this fundamental limitation, we present the first extension of normalizing flows to hyperbolic spaces. We first elevate normalizing flows to hyperbolic spaces using coupling transforms defined on the tangent bundle, termed Tangent Coupling ($\mathcal{TC}$). We further introduce Wrapped Hyperboloid Coupling ($\mathcal{W}\mathbb{H}C$), a fully invertible and learnable transformation that explicitly utilizes the geometric structure of hyperbolic spaces, allowing for expressive posteriors while being efficient to sample from. We demonstrate the efficacy of our novel normalizing flow over hyperbolic VAEs and Euclidean normalizing flows. Our approach achieves improved performance on density estimation, as well as reconstruction of real-world graph data, which exhibit a hierarchical structure. Finally, we show that our approach can be used to power a generative model over hierarchical data using hyperbolic latent variables.