This paper suggests a model for the motion of tagged pedestrians: pedestrians moving towards a specified targeted destination, which they are forced to reach. It aims to be a decision-making tool for the positioning of fire fighters, security personnel and other services in a pedestrian environment. Taking interaction with the surrounding crowd into account leads to a differential nonzero-sum game model where the tagged pedestrians compete with the surrounding crowd of ordinary pedestrians. When deciding how to act, pedestrians consider crowd distribution-dependent effects, like congestion and crowd aversion. Including such effects in the parameters of the game, makes it a mean-field type game. The equilibrium control is characterized, and special cases are discussed. Behavior in the model is studied by numerical simulations.MSC 2010: 49N90, 49J55, 60H10, 60K30, 91A80, 93E20 Financial support from the Swedish Research Council (2016-04086) is gratefully acknowledged. We thank the anonymous reviewers for comments and suggestions that greatly helped to improve the presentation of the results, and we thank E. Cristiani for directing us to [23].Aurell, Djehiche/Tagged pedestrian model 2 the model include cancer cell dynamics and smart medicine in the human body, and malware propagation in a network, among other.The central planner's decision making is based on knowledge of the pedestrian distribution. As noted in [45], the pedestrian behavior in dense crowds is empirically random to some extent, likely due to the large number of external inputs. In a noisy environment, the central planner anticipates the behavior of the crowd and predicts the tagged's path to the target. As is standard in the mean-field approach, interaction with tagged and ordinary pedestrians is modeled as reactions to the state distribution of a representative tagged and ordinary pedestrian, respectively. This leads us to formulate a mean-field type game based model, which in certain scenarios reduces to an optimal control based model.
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Optimal control and games of mean-field typeRational pedestrian behavior is, in this paper, characterized by either a game equilibrium, or an optimal control. The tool used to find the equilibrium/optimal behavior is Pontryagin's stochastic maximum principle (SMP). For stochastic control problems, SMP yields, when available, necessary conditions that must be satisfied by any optimal solution. The necessary conditions become sufficient under additional convexity conditions. Early results show that an optimal control along with the corresponding optimal state trajectory must solve the so-called Hamiltonian system, which is a two-point (forward-backward) boundary value problem, together with a maximum condition of the so-called Hamiltonian function (see [51] for a detailed account). In stochastic differential games, both zero-sum and nonzero-sum, SMP is one of the main tools for obtaining conditions for an equilibrium, essentially inherited from the theory of stochastic optimal control. For recent examples ...