We characterize the product line choice and pricing of a monopolist as the upper envelope of net marginal revenue curves to the individual product demand functions. The equilibrium product varieties to include in a product line are those yielding the highest upper envelope. In a central case (corresponding to a generalized vertical differentiation framework), the equilibrium range of...

We reconsider Stackelberg’s classical critique of the Cournot duopoly, in the framework of endogenous timing for two-player games. For quantity duopoly we provide different sets of minimal conditions, directly on the demand and cost functions, yielding respectively the simultaneous and the two sequential modes of play. While our findings essentially confirm the predominance of the former, they ...

This paper examines irreversible investment in a project with uncertain returns, when there is an advantage to being the first to invest, and externalities to investing when others also do so. Pre-emption decreases and may even eliminate the option values created by irreversibility and uncertainty. Externalities introduce inefficiencies in investment decisions. Pre-emption and externalities com...

This paper estimates the implicit model, especially the roles of size asymmetries and firm numbers, used by the European Commission to identify mergers with coordinated effects. This subset of cases offers an opportunity to shed empirical light on the conditions where a Competition Authority believes tacit collusion is most likely to arise. We find that, for the Commission, tacit collusion is a...

We characterize equilibria of games with two properties: (i) Agents have the opportunity to adjust their strategic variable after their initial choices and before payoffs occur; but (ii) they can only add to their initial amounts. The equilibrium set consists of just the Cournot–Nash outcome, one or both Stackelberg outcomes, or a continuum of points including the Cournot– Nash outcome and one ...

I describe the entry process in a spatial market over an in...nite time horizon. I show that, as long as the strategy space at the location stage is unbounded, the results derived from the single-period Stackelberg model of entry coincide with those obtained in the in...nite horizon model. On the contrary, if the strategy space is bounded, then the later the follower enters, the closer to the c...

The arm’s length principle states that the transfer price between two associated enterprises should be the price that would be paid for similar goods in similar circumstances by unrelated parties dealing at arm’s length with each other. This paper examines the effect of the arm’s length principle on dynamic competition in imperfectly competitive markets. It is shown that the arm’s length princi...

We show that whether trade is one-way or two-way depends on wage strategies adopted by trade unions. The union’s wage strategy choices themselves depend upon the conditions under which trade takes place, as well as upon the characteristics of both the labour and the product markets in the trading countries. The impact of economic integration on union choices and therefore upon both labour marke...

This paper studies repeated games with privately observed signals where it is feasible but costly to observe other players’ past actions accurately. At the end of each period, players decide the set of players to monitor by paying the corresponding observation costs. We show that the folk theorem holds for any finite stage game that satisfies the fulldimensionality condition and a minimal disti...

This paper analyzes dynamic cartel formation and antitrust enforcement when firms operate in demand-related markets. We show that cartel prosecution can have a knock-on effect: desisting a cartel in one market reduces profits and cartel stability and leads to the break-up of the cartel in the adjacent market. Cartel prosecution can also have a waterbed effect: desisting a cartel increases carte...