# Professor Massimo Fornasier: Sparse mean field optimal control

Professor Massimo Fornasier, from the Technical University of Munich, is visiting the department /CMA. This is his second lecture.

Starting with the seminal papers of Reynolds (1987), Vicsek et. al. (1995) Cucker-Smale (2007), there has been a flood of

recent works on models of self-alignment and consensus dynamics. Self-organization has been so far the main driving concept.

However, the evidence that in practice self-organization does not necessarily occur leads to the natural question of whether it is

possible to externally influence the dynamics in order to promote the formation of certain desired patterns. Once this fundamental question

is posed, one is also faced with the issue of defining the best way of obtaining the result, seeking for the most “economical” manner to achieve

a certain outcome. The first part of this talk precisely addresses the issue of finding the sparsest control strategy for finite dimensional models

in order to lead us optimally towards a given outcome. In the second part of the talk we introduce the rigorous limit process connecting finite

dimensional sparse optimal control problems with ODE constraints to an infinite dimensional optimal control problem with a constraint given

by a system of ODE for the leaders coupled with a PDE of Vlasov-type, governing the dynamics of the probability distribution of the followers.

The technical derivation of the sparse mean-field optimal control is realized by the simultaneous development of the mean-field limit of the

equations governing the followers dynamics together with the Gamma-limit of the finite dimensional sparse optimal control problems.

Suggested literature:

http://www-m15.ma.tum.de/foswiki/pub/M15/Allgemeines/PublicationsEN/flocking_V9.pdf

http://www-m15.ma.tum.de/foswiki/pub/M15/Allgemeines/PublicationsEN/arxiv.pdf

http://www-m15.ma.tum.de/foswiki/pub/M15/Allgemeines/PublicationsEN/smfoc_sub.pdf