A single player and a mass of agents: a pursuit evasion-like game
Fabio Bagagiolo, Rossana Capuani, Luciano Marzufero
TL;DR
We address a zero-sum pursuit-evasion-like differential game where a single agent competes against a mass whose density evolves under a transport-type continuity equation. The authors derive an infinite-dimensional Hamilton-Jacobi-Isaacs equation on a viable Hilbert-space subset and prove that the lower value function is the unique viscosity solution via a Dynamic Programming Principle based on non-anticipating strategies. They establish regularity and compactness properties for the density $m$, define a viable domain $\tilde{X}$ to avoid boundary complications, and formulate the HJI equation with a corresponding viscosity framework, including a comparison principle for uniqueness. The paper also illustrates the framework with two one-dimensional examples to shed light on the structure of optimal strategies in simplified settings and to connect with mean-field-type considerations. Overall, the results advance the theory of infinite-dimensional viscosity solutions for differential games with distributed mass dynamics and open avenues for mean-field game interpretations and applications.
Abstract
We study a finite-horizon differential game of pursuit-evasion like, between a single player and a mass of agents. The player and the mass directly control their own evolution, which for the mass is given by a first order PDE of transport equation type. Using also an adapted concept of non-anticipating strategies, we derive an infinite dimensional Isaacs equation, and by dynamic programming techniques we prove that the value function is the unique viscosity solution on a suitable invariant subset of a Hilbert space.
