Atoms Revisited - The Oligopoly Equivalence Theorem

General Equilibrium
Market Structure

Article

Is an economy with atoms perfectly competitive or, more accurately, does it yield the same result we obtain in a perfectly competitive economy? The answer, it turns out, is a resounding "Yes!" -- under certain conditions on the size and character of the "atoms". This surprising "oligopoly equivalence" result was first unearthed by Michael J. Farrell (1970) in the context of a Debreu-Scarf replica economy and by Jean-Jaskold Gabszewicz and Jean-Francois Mertens (1971) and Benyamin Shitovitz (1973) in the Aumann continuum economy.