Do oligopolists always compete on the basis of price?

No, oligopolists do not always compete on the basis of price. While price competition is one strategy, firms in an oligopoly often engage in non-price competition by differentiating their products, enhancing customer service, or investing in advertising. This is because price wars can erode profits for all firms involved, leading them to seek other competitive advantages. Ultimately, the nature of competition in an oligopoly depends on the market dynamics and the specific strategies of the firms involved.