We derive sufficient and necessary optimality conditions in terms of a stochastic maximum principle (SMP) for controls associated with cost functionals of mean-field type, under dynamics driven by a class of Markov chains of mean-field type which are pure jump processes obtained as solutions of...

In this paper, we see how much the average monthly frequency of price changes ties down the behavior of firms in steady-state in terms of the average length of price-spells across firms. We use the UK CPI data at the aggregate and sectoral level and find that the actual mean is about twice the...