This book provides a methodology for the analysis of oligopolistic markets from an equilibrium viewpoint, considering competition within and between groups of firms. It proposes a well-founded measure of competitive toughness that can be used in empirically relevant applications. This measure reflects the weight put by each firm on competition for market share relative to competition for market size – two dimensions of competition involving conflicting and convergent interests, respectively. It further explores several applications, such as the effect of tougher competition on innovation...