用神经跳跃微分方程建模随机过程,无需对抗训练即可生成真实数据分布。
Neural Jump ODEs as Generative Models
- 基于离散观测数据学习Itô过程的漂移与扩散系数。
- 在极限情况下可恢复真实参数,生成样本分布与原过程一致。
- 适合处理不规则采样、缺失值和路径依赖场景,适用于真实世界数据。
本文研究如何将神经跳跃微分方程(NJODE)作为Itô过程的生成模型。给定固定Itô过程的离散观测样本,NJODE框架可用于逼近该过程的漂移和扩散系数。在标准正则性假设下,我们证明在极限情况下可恢复真实参数。因此,利用学习到的系数对相应Itô过程采样,生成的样本在极限下与真实过程同分布。相比其他生成模型,本方法无需对抗训练,仅需在观测样本上进行预测建模,无需训练时生成样本以近似分布。此外,NJODE天然支持不规则采样、缺失值及路径依赖动态,适用于真实场景。当Itô过程系数具有路径依赖性时,NJODE可基于历史观测学习最优近似,从而实现对不完整、不规则历史数据的条件生成。
原文摘要 · Abstract (English)
In this work, we explore how Neural Jump ODEs (NJODEs) can be used as generative models for Itô processes. Given (discrete observations of) samples of a fixed underlying Itô process, the NJODE framework can be used to approximate the drift and diffusion coefficients of the process. Under standard regularity assumptions on the Itô processes, we prove that, in the limit, we recover the true parameters with our approximation. Hence, using these learned coefficients to sample from the corresponding Itô process generates, in the limit, samples with the same law as the true underlying process. Compared to other generative machine learning models, our approach has the advantage that it does not need adversarial training and can be trained solely as a predictive model on the observed samples without the need to generate any samples during training to empirically approximate the distribution. Moreover, the NJODE framework naturally deals with irregularly sampled data with missing values as well as with path-dependent dynamics, allowing to apply this approach in real-world settings. In particular, in the case of path-dependent coefficients of the Itô processes, the NJODE learns their optimal approximation given the past observations and therefore allows generating new paths conditionally on discrete, irregular, and incomplete past observations in an optimal way.
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