ABSTRACT
In 1980 the analysis of barriers to entry seen as competitive strategies, as opposed to price theory, began to take shape. In order to a better illustrate the Industrial Organization theory, it is convenient to introduce three main methodological branches: strategy competitive; contestable markets; and game theory. The consequences of deregulation of markets were different, depending on the industry and connected with the market structure. In the topic at hand predation and limit price theory explain to deterrence entry into a market, the controversy was quite relevant in political issues. The principal reason was the evolution of economic theory through the use of games in order to prove authors proposals. Industrial concentration is a controversial barrier to entry; it has scholars which defend it come hell or high water and cast-iron opponents as well. These entry models receive a separate consideration of capacity and concentration since Kamien-Schwartz's 1975 article; using the Cournot model.
