We investigate the issue of strategic substitutability/complementarity in differential games. We prove that instantaneous best replies exist if Hamiltonian functions are multiplicative in the control variables. Otherwise, if the Hamiltonians are addively separable w.r.t. controls, a dominant...

We investigate the issue of strategic substitutability/complementarity in a Cournot differential game with sticky prices. We show that first order conditions do not produce instantaneous best reply functions. However, we identify negatively sloped reaction functions in steady state, with the...