Complete information game

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In mathematical game theory, a game with complete information describes a game in which all players are fully familiar with the rules of the game: which player has which decision options under which circumstances? Which payouts result from which sequences of player decisions?

The property of complete information should always be fulfilled in "normal" board games such as chess and skat . When modeling an economic process through a game, however, the property of complete information cannot always be assumed. In this respect, game theory also explicitly examines games with incomplete information , for which the rules are not generally known. These are called Bayesian games .

Difference to perfect information

Not to be confused with complete information in a game is perfect information , sometimes referred to as perfect information . This property of a game means that the players are always informed about what has happened so far, as is typically the case with board games , including those with a random influence such as backgammon , but not with most card games .

However, some authors describe the property of perfect information, deviating from the scientific standard, as complete information .

Complete information game in business

In the case of economic problems, which have been and are often investigated using game theory approaches, games are almost exclusively encountered without complete information, since, for example, economic key data and plans of competing companies are generally not known. However, as Harsanyi showed in 1967, if one has reasonable estimates, one can introduce a virtual random player in such situations - from the perspective of the investigator it does not matter whether the opponent probably has plan X or later throws him out with the corresponding probability. The advantage of this dialectical trick is that such games with complete, but imperfect information, are much easier to understand and treat in game theory.

Individual evidence

  1. Werner Güth: Game theory and economic (examples) games , 2nd edition, 1999, ISBN 3540652116 , doi : 10.1007 / 978-3-642-58437-4 , p. 125.
  2. Gernot Sieg: Game Theory , 2nd edition, 2005, ISBN 3486275267 , p. 90.
  3. Elwyn R. Berlekamp , John H. Conway , Richard K. Guy : Winning . Braunschweig, 1985, Volume 1, ISBN 3528085312 , doi : 10.1007 / 978-3-322-83170-5 , p. 16. The original version of Winning Ways speaks of complete information .
  4. Engl .: complete information
  5. ^ John C. Harsanyi : Games with incomplete information played by "Bayesian" players, Part I. The Basic Model . Pp. 159-182, JSTOR 2628393