Duopoly

A duopoly (from Greek δύο, duo (two) + πωλεῖν, polein (to sell)) is a type of oligopoly where two firms have dominant or exclusive control over a market. It is the most commonly studied form of oligopoly due to its simplicity. Duopolies sell to consumers in a competitive market where the choice of an individual consumer can not affect the firm. The defining characteristic of both duopolies and oligopolies is that decisions made by sellers are dependent on each other. A duopoly (from Greek δύο, duo (two) + πωλεῖν, polein (to sell)) is a type of oligopoly where two firms have dominant or exclusive control over a market. It is the most commonly studied form of oligopoly due to its simplicity. Duopolies sell to consumers in a competitive market where the choice of an individual consumer can not affect the firm. The defining characteristic of both duopolies and oligopolies is that decisions made by sellers are dependent on each other. There are two principal duopoly models, Cournot duopoly and Bertrand duopoly: Modern American politics, in particular the electoral college system, has been described as duopolistic since the Republican and Democratic parties have dominated and framed policy debate as well as the public discourse on matters of national concern for about a century and a half. Third Parties have encountered various blocks in getting onto ballots at different levels of government as well as other electoral obstacles, such as denial of access to general election debates. Since 1987, the Commission on Presidential Debates, established by the Republican and Democratic parties themselves, supplanting debates run since 1920 by the League of Women Voters. The League withdrew its support in protest in 1988 over objections of alleged stagecraft such as rules for camera placement, filling the audience with supporters, approved moderators, predetermined question selection, room temperature and others. The Commission maintains its own rules for admittance and has yet to admit a third party candidate to a televised debate. A commonly cited example of a duopoly is that involving Visa and MasterCard, who between them control a large proportion of the electronic payment processing market. In 2000 they were the defendants in a U.S. Department of Justice antitrust lawsuit. An appeal was upheld in 2004.