“…It can be generally intended as a measure of the influence of an agent, accounting for a number of different interpretations according to the context. Similar background variables have been used in recent literature to describe wealth distribution [26,28,43], degree of knowledge [16,17], degree of connectivity of an agent in a network [6,15], and also applications to opinion formation [29], just to name a few. Comparing to these other approaches, our mean-field approximation (1.3), (1.4) features a more profound interplay between the variable λ and the spatial distribution x of the agents, resulting in a higher flexibility of the model: not only is λ changing in time, but its variation is driven by an optimality principle steered by the controls.…”