During our studies of market structures we have come across oligopolies. We have found that in this form of structure there can be both collusive and non-collusive markets. It is important to remember that this means that we also have more than one model to help us explain and analyse this form of structure. We have so far concentrated upon non-collusive markets and the kinked-demand curve model (don’t forget this is also know as the ‘sticky prices’ model). As a quick reminder of what we have studied so far, here is a short presentation.