2020年度

Math-Fi seminar on 23 Apr.

2020.04.23 Thu up
  • Date:  23 Apr. (Thu.)
  • Place: On the Web
  • Time: 16:30-18:00
  • Speaker: Dai Taguchi (Okayama University)
  • Title: Multi-dimensional Avikainen’s estimates
  • Abstract:
Avikainen provided a sharp upper bound of the expectation of |f(X)-f(Y)|^{q} by the expectation of |X-Y|^{p}, for any one-dimensional random variables X with bounded density and Y, and function of bounded variation f. In this talk, we consider multi-dimensional analogues of this estimate for any function of bounded variation in R^{d}, Orlicz–Sobolev spaces, Sobolev spaces with variable exponents or fractional Sobolev spaces.

We apply main statements to the numerical analysis on irregular functional of a solution to stochastic differential equations based on the Euler–Maruyama scheme and the multilevel Monte Carlo method, and L^{2}-time regularity of decoupled forward–backward stochastic differential equations with irregular terminal conditions.

This is joint work with Akihiro Tanaka (Osaka university) and Tomooki Yuasa (Ritsumeikan University).

Math-Fi seminar on 9 Apr.

2020.04.09 Thu up
  • Date: 9 Apr. (Thu.)
  • Place: On the Web
  • Time: 16:30-18:00
  • Speaker: Pierre Bras (École normale supérieure Paris)
  • Title: Acceleration of stochastic optimization algorithms
  • abstract: 
I will introduce stochastic algorithms to solve optimization problems, arising in machine learning or mathematical finance. Then, starting with the basic stochastic gradient algorithm, we will see how one can modify it so that to accelerate the convergence towards the optimal solution.