Assuming constant marginal cost, it is shown that a switch from specific to ad valorem taxation has no effect on the critical discount factor required to sustain collusion. This result is shown to hold for Cournot oligopoly as well as for Bertrand oligopoly when collusion is sustained with...

We show that the static duopoly model in which firms choose between exporting and foreign direct investment is often a prisoners' dilemma game in which a switch from exporting to foreign direct investment reduces profits. By contrast, we show that when the game is repeated there is a range of...