It is well known that the equilibrium solution of oligopoly games with isoelastic
demand functions can be indeterminate. I revisit this issue through
an open-loop differential game approach based on the assumption of sticky
prices, to show that indeterminacy arises only in steady state, in the limit
case where marginal costs tend to zero. Otherwise, at any time during the
game, Pontryagin’s Maximum Principle ensures the existence of a unique
and well defined solution, irrespective of the size of marginal costs. Finally,
I show that an analogous result holds in the feedback case, although the
Bellman equation of the representative firm cannot be solved analytically
