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克服维度诅咒:从非线性蒙特卡罗到深度学习

Overcoming the curse of dimensionality: from nonlinear Monte Carlo to deep learning
课程网址: https://videolectures.net/8ecm2021_jentzen_munster_curse/  
主讲教师: Arnulf Jentzen
开课单位: 8ECM会议
开课时间: 2021-07-06
课程语种: 英语
中文简介:
偏微分方程(PDE)是用于模拟自然界和人造复杂系统问题的最通用工具之一。例如,随机偏微分方程是化学工程和天气预报中非线性滤波问题模型的基本组成部分,确定性Sc[url]roedinger偏微分方程描述量子物理系统中的波函数,确定性Hamiltonian Jacobi-Bellman偏微分方程在运筹学中用于描述公司以最小化成本为目标的最优控制问题,确定性Black-Sc[url]oles型偏微分方程广泛应用于投资组合优化模型以及最先进的金融衍生品定价和对冲模型。出现在此类模型中的偏微分方程通常是高维的,因为粗略地说,维度的数量对应于模型中所有涉及的相互作用物质、粒子、资源、代理或资产的数量。例如,在上述金融工程模型的情况下,PDE的维度通常对应于所涉及的对冲投资组合中的金融资产的数量。这种偏微分方程通常不能明确求解,并且开发能够近似计算高维偏微分方程解的近似算法是应用数学中最具挑战性的任务之一。文献中几乎所有的偏微分方程近似算法都存在所谓的“维数诅咒”,即近似算法实现给定近似精度所需的计算操作数量在所考虑的偏微分函数的维度上呈指数级增长。使用这种算法,即使使用当前最快的计算机,也不可能近似计算高维偏微分方程的解。在线性抛物型偏微分方程和固定时空点近似的情况下,可以通过蒙特卡罗近似算法和Feynman-Kac公式来克服维数的诅咒。在本文中,我们证明了在一类一般的双线性抛物型偏微分方程的情况下,适当的深度神经网络近似确实克服了维数的诅咒,从而首次证明了在没有维数诅咒的情况下可以近似求解一般的半线性抛物型偏分方程。克拉夫迪贾·库特纳,普里莫尔斯卡大学校长兼8ECS组委会副主席,托马日·皮桑斯基,8ECS组委会主席内日卡·姆拉莫尔·科斯塔,DMFA主席,其中一位数学家。《全欧洲的数学女性》是一个巡回展览,其起点是2016年7月在柏林举行的第七届ECM。然而,它被扩展到8ECM,引入了来自欧洲-地中海地区的数学家。还可在以下网址订购介绍所有演讲者的新目录:[url]ttps://womeninmat[url].net/catalogue/该展览是5月12日运动的一部分,该运动旨在庆祝数学界的女性,并在全球推广120项活动。该运动于2018年7月31日在里约热内卢举行的世界数学妇女大会(WM)2上发起,以纪念玛丽亚姆·米尔扎哈尼的生日。
课程简介: Partial differential equations (PDEs) are among the most universal tools used in modelling problems in nature and man-made complex systems. For example, stochastic PDEs are a fundamental ingredient in models for nonlinear filtering problems in chemical engineering and weather forecasting, deterministic Schroedinger PDEs describe the wave function in a quantum physical system, deterministic Hamiltonian-Jacobi-Bellman PDEs are employed in operations research to describe optimal control problems where companys aim to minimise their costs, and deterministic Black-Scholes-type PDEs are highly employed in portfolio optimization models as well as in state-of-the-art pricing and hedging models for financial derivatives. The PDEs appearing in such models are often high-dimensional as the number of dimensions, roughly speaking, corresponds to the number of all involved interacting substances, particles, resources, agents, or assets in the model. For instance, in the case of the above mentioned financial engineering models the dimensionality of the PDE often corresponds to the number of financial assets in the involved hedging portfolio. Such PDEs can typically not be solved explicitly and it is one of the most challenging tasks in applied mathematics to develop approximation algorithms which are able to approximatively compute solutions of high-dimensional PDEs. Nearly all approximation algorithms for PDEs in the literature suffer from the so-called ”curse of dimensionality” in the sense that the number of required computational operations of the approximation algorithm to achieve a given approximation accuracy grows exponentially in the dimension of the considered PDE. With such algorithms it is impossible to approximatively compute solutions of high-dimensional PDEs even when the fastest currently available computers are used. In the case of linear parabolic PDEs and approximations at a fixed space-time point, the curse of dimensionality can be overcome by means of Monte Carlo approximation algorithms and the Feynman-Kac formula. In this talk we prove that suitable deep neural network approximations do indeed overcome the curse of dimensionality in the case of a general class of semilinear parabolic PDEs and we thereby prove, for the first time, that a general semilinear parabolic PDE can be solved approximatively without the curse of dimensionality. Klavdija Kutnar, Rector of the University of Primorska and 8ECM Organizing committee Deputy Chair, Tomaž Pisanski, 8ECM Organizing Committee Chair Nežka Mramor Kosta, President of DMFA and one of the portrayed mathematicians. Women of Mathematics throughout Europe is a touring exhibition whose starting point was the 7th ECM held in July 2016 in Berlin. It was, however, extended for the 8ECM, introducing mathematicians from the Euro-Mediterranean region.  The exhibition is a part of the May12 movement, which celebrates Women in Mathematics and promotes 120 events worldwide. The movement was initiated on 31st July 2018 at the World Meeting for Women in Mathematics, (WM)2 in Rio de Janeiro in memory of Maryam Mirzakhani’s birthday.
关 键 词: 维度诅咒; 非线性蒙特卡罗; 深度学习
课程来源: 视频讲座网
数据采集: 2024-05-23:liyq
最后编审: 2024-05-23:liyq
阅读次数: 6