Fourier Galerkin approximation of mean field control problems

Fuente: arXiv
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Main Authors: Delarue, François, Martini, Mattia
Format: Preprint
Published: 2024
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_version_ 1866910727631011840
author Delarue, François
Martini, Mattia
author_facet Delarue, François
Martini, Mattia
contents The purpose of this work is to provide a finite dimensional approximation of the solution to a mean field optimal control problem set on the $d$-dimensional torus. The approximation is obtained by means of a Fourier-Galerkin method, the main principle of which is to convolve probability measures on the torus by the Dirichlet kernel or, equivalently, to truncate the Fourier expansion of probability measures on the torus. However, this operation has the main feature not to leave the space of probability measures invariant, which drawback is know as \textit{Gibbs}' phenomenon. In spite of this, we manage to prove that, for initial conditions in the `interior' of the space of probability measures and for sufficiently large levels of truncation, the Fourier-Galerkin method induces a new finite dimensional control problem whose trajectories take values in the space of probability measures with a finite number of Fourier coefficients. Our main result asserts that, whenever the cost functionals are smooth and convex, the distance between the optimal trajectories of the original and approximating control problems decreases at a polynomial rate as the index of truncation in the Fourier-Galerkin method tends to $\infty$. A similar result holds for the distance between the corresponding value functions. From a practical point of view, our approach provides an efficient strategy to approximate mean field control optimizers by finite dimensional parameters and opens new perspectives for the numerical analysis of mean field control problems. It may be also applied to discretize more general mean field game systems.
format Preprint
id arxiv_https___arxiv_org_abs_2403_15642
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Fourier Galerkin approximation of mean field control problems
Delarue, François
Martini, Mattia
Optimization and Control
Analysis of PDEs
Probability
49N80, 49L12, 35Q93, 42B05
The purpose of this work is to provide a finite dimensional approximation of the solution to a mean field optimal control problem set on the $d$-dimensional torus. The approximation is obtained by means of a Fourier-Galerkin method, the main principle of which is to convolve probability measures on the torus by the Dirichlet kernel or, equivalently, to truncate the Fourier expansion of probability measures on the torus. However, this operation has the main feature not to leave the space of probability measures invariant, which drawback is know as \textit{Gibbs}' phenomenon. In spite of this, we manage to prove that, for initial conditions in the `interior' of the space of probability measures and for sufficiently large levels of truncation, the Fourier-Galerkin method induces a new finite dimensional control problem whose trajectories take values in the space of probability measures with a finite number of Fourier coefficients. Our main result asserts that, whenever the cost functionals are smooth and convex, the distance between the optimal trajectories of the original and approximating control problems decreases at a polynomial rate as the index of truncation in the Fourier-Galerkin method tends to $\infty$. A similar result holds for the distance between the corresponding value functions. From a practical point of view, our approach provides an efficient strategy to approximate mean field control optimizers by finite dimensional parameters and opens new perspectives for the numerical analysis of mean field control problems. It may be also applied to discretize more general mean field game systems.
title Fourier Galerkin approximation of mean field control problems
topic Optimization and Control
Analysis of PDEs
Probability
49N80, 49L12, 35Q93, 42B05
url https://arxiv.org/abs/2403.15642