In this paper we consider a model of oligopolistic competition where firms make a two-dimensional product line decision. They choose a location in style space, thus inducing horizontal differentiation, and produce different qualities (a product line) of a given good (vertical differentiation),...

In this paper we consider a model of group formation where group of individuals may have different feasible sets. We focus on two polar cases, increasing returns, when the set of feasible alternatives increases if a new member joins the group, and decreasing returns, when a new member has an...

This paper investigates efficiency and equitability issues given a cost sharing method f in an economy with a public commodity. We introduce the basic concept of a f-Lindahl equilibrium and study the set of all these particular equilibrium allocations. It then turns out that this set is...

The central result of this paper is a refinement of an equivalence theorem in Mas-Colell (1980) for the core of a finite economy with a public good. It is shown that an allocation belongs to the core if and only if it is a cost share equilibrium. A further characterization of core elements which...

This paper examines a model of an infinite production economy with a finite number of types of agents and semi-public goods, where utility of a member of a coalition depends not only on the vector of public commodities produced by this coalition, but also on the structure of the coalition. The...