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arXiv 1908.00533math.OCcs.LGcs.SYeess.SY
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随机系统密度传播的梯度流算法

Gradient Flow Algorithms for Density Propagation in Stochastic Systems

University of California, Santa Cruz(加州大学圣克鲁兹分校)

Kenneth F. Caluya, Abhishek Halder

摘要:

我们开发了一个新的计算框架来解决连续时间随机非线性系统中控制联合密度函数(PDF)流动的偏微分方程(PDE)。在不确定性传播、非线性滤波和随机控制中,需要计算服从先验动力学的瞬态联合PDF。我们的方法打破了传统的空间离散化或函数逼近的方法-这两种方法,在一般情况下,遭受的“维数灾难”。在该框架中,我们离散时间,但不是状态空间。我们解决了无穷维邻近递归的联合PDF,在小的时间步长限制,这在理论上相当于解决底层的运输偏微分方程的流形。由此产生的计算有一定的自由能功能的梯度流的几何解释相对于Wasserstein度量所产生的最佳质量输运理论。我们表明,随着熵正则化的对偶,导致一个锥保持不动点递归被证明是压缩的汤普森度量。提出了一种块坐标迭代格式,以保证收敛性的方式求解所得到的非线性递推式。这种方法使得非参数瞬态联合PDF传播的计算速度非常快。数值例子和各种扩展来说明所提出的方法的范围和有效性。

英文摘要:

We develop a new computational framework to solve the partial differential equations (PDEs) governing the flow of the joint probability density functions (PDFs) in continuous-time stochastic nonlinear systems. The need for computing the transient joint PDFs subject to prior dynamics arises in uncertainty propagation, nonlinear filtering and stochastic control. Our methodology breaks away from the traditional approach of spatial discretization or function approximation -- both of which, in general, suffer from the "curse-of-dimensionality". In the proposed framework, we discretize time but not the state space. We solve infinite dimensional proximal recursions in the manifold of joint PDFs, which in the small time-step limit, is theoretically equivalent to solving the underlying transport PDEs. The resulting computation has the geometric interpretation of gradient flow of certain free energy functional with respect to the Wasserstein metric arising from the theory of optimal mass transport. We show that dualization along with an entropic regularization, leads to a cone-preserving fixed point recursion that is proved to be contractive in Thompson metric. A block co-ordinate iteration scheme is proposed to solve the resulting nonlinear recursions with guaranteed convergence. This approach enables remarkably fast computation for non-parametric transient joint PDF propagation. Numerical examples and various extensions are provided to illustrate the scope and efficacy of the proposed approach.

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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