arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2201.13094cs.LGcs.NEmath.MGmath.PRq-fin.CP
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设计通用因果深度学习模型:几何(超)Transformer

Designing Universal Causal Deep Learning Models: The Geometric (Hyper)Transformer

Beatrice Acciaio, Anastasis Kratsios, Gudmund Pammer

摘要:

随机分析中的几个问题是通过它们的几何结构来定义的,保持这种几何结构对于生成有意义的预测是必不可少的。然而,如何设计能够对这些几何结构进行编码的原则性深度学习(DL)模型在很大程度上仍然是未知的。我们解决这个开放的问题,通过引入一个通用的因果几何DL框架中,用户指定一个合适的度量空间$\mathscr{X}$和$\mathscr{Y}$和我们的框架返回一个DL模型能够因果近似任何"正规“的映射发送时间序列在$\mathscr{X}^{\mathbb{Z}}$的时间序列在$\mathscr{Y}^{\mathbb{Z}}$,同时尊重他们的信息在整个时间的前向流。在$\mathscr{Y}$上合适的几何包括各种(适应的)Wasserstein空间在最优停止问题中出现,各种描述连续时间有限状态马尔可夫链的条件分布的统计流形,以及所有允许Schauder基的Fréchet空间,例如在经典金融中。合适的空间$\mathscr{X}$是任何欧几里得空间的紧致子集。我们的研究结果都定量地表达了我们的DL模型,以实现一个给定的近似误差作为目标映射的规则性和几何结构的函数的$\mathscr{X}$和$\mathscr{Y}$的参数的数量。即使在省略任何时间结构时,我们的通用逼近定理也是第一个保证,即定义在这种$\mathscr{X}$和$\mathscr{Y}$之间的Hölder函数可以由DL模型逼近。

英文摘要:

Several problems in stochastic analysis are defined through their geometry, and preserving that geometric structure is essential to generating meaningful predictions. Nevertheless, how to design principled deep learning (DL) models capable of encoding these geometric structures remains largely unknown. We address this open problem by introducing a universal causal geometric DL framework in which the user specifies a suitable pair of metric spaces $\mathscr{X}$ and $\mathscr{Y}$ and our framework returns a DL model capable of causally approximating any ``regular'' map sending time series in $\mathscr{X}^{\mathbb{Z}}$ to time series in $\mathscr{Y}^{\mathbb{Z}}$ while respecting their forward flow of information throughout time. Suitable geometries on $\mathscr{Y}$ include various (adapted) Wasserstein spaces arising in optimal stopping problems, a variety of statistical manifolds describing the conditional distribution of continuous-time finite state Markov chains, and all Fréchet spaces admitting a Schauder basis, e.g. as in classical finance. Suitable spaces $\mathscr{X}$ are compact subsets of any Euclidean space. Our results all quantitatively express the number of parameters needed for our DL model to achieve a given approximation error as a function of the target map's regularity and the geometric structure both of $\mathscr{X}$ and of $\mathscr{Y}$. Even when omitting any temporal structure, our universal approximation theorems are the first guarantees that Hölder functions, defined between such $\mathscr{X}$ and $\mathscr{Y}$ can be approximated by DL models.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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