计算与应用数学拔尖博士生系列论坛——Stochastic Optimization for Distributed Elliptic Control Problems
报告人：Qi Sun (Peking University)
地点：Room 1493, Sciences Building No. 1
Abstract: We study a distributed optimal control problem, in which the governing system is given by second-order elliptic equations with log-normal coefficients. To lessen the curse of dimensionality that originates from the representation of stochastic coefficients, the Monte Carlo finite element method is adopted for numerical discretization where a large number of sampled constraints are involved. For the solution of such a large-scale optimization problem, stochastic gradient descent method is widely used but has slow convergence asymptotically due to its inherent variance. To remedy this problem, we adopt an averaged stochastic gradient descent method which performs stably even with the use of relatively large step sizes and small batch sizes. Moreover, adaptive step sizes for each component of the numerical solution are considered to promote convergence. Numerical experiments are carried out to validate our theoretical findings.