Tonin, Simone
(2015)
Strategic foundations of oligopolies in general equilibrium.
PhD thesis, University of Glasgow.
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Abstract
In this thesis, I study the strategic foundations of oligopolies in general equilibrium by following the approach based on strategic market games. The thesis is organised as follows.
In Chapter 1, I first survey some of the main contributions on imperfect competition in production economies and the main problems which arise in this framework. I then focus on the literature on imperfect competition in exchange economies by considering the CournotWalras approach and strategic market games. I finally discuss the main contributions on the foundations of oligopolies.
In Chapter 2, I extend the noncooperative analysis of oligopoly to exchange economies with infinitely many commodities and traders by using a strategic market game with trading posts. I prove the existence of a CournotNash equilibrium with trade and show that the price vector and the allocation at the CournotNash equilibrium converge to the Walras equilibrium when the number of traders increases. In a framework with infinitely many commodities, an oligopolist can be an "asymptotic oligopolist" if his market power is uniformly bounded away from zero on an infinite set of commodities, or an "asymptotic pricetaker" if his market power converges to zero along the sequence of commodities. The former corresponds to the Cournotian idea of oligopolist. The latter describes an agent with a kind of mixed behaviour since his market power can be made arbitrary small by choosing an appropriate infinite set of commodities while it is greater than a positive constant on a finite set.
In Chapter 3, I further study oligopolies in economies with infinitely many commodities and traders. By using the strategic market game called "all for sale model", I prove the existence of an asymptotic pricetaker. Heuristically, an asymptotic pricetaker exists if at least one trader makes positive bids on an infinite number of commodities and in all markets the quantities of commodities exchanged are nonnegligible.
In Chapter 4, I study if there is a nonempty intersection between the sets of CournotNash and Walras allocations in mixed exchange economies, with oligopolists represented as atoms and small traders represented by a continuum. In a bilateral oligopoly setting, I show that a necessary and sufficient condition for a CournotNash allocation to be a Walras allocation is that all atoms demand a null amount of one of the two commodities. I also provide four examples which show that this characterization holds nonvacuously.
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