bimatrix game
class="infobox"
| c & d & e \\ f & g & h \\ \end{bmatrix} | p & q & r \\ s & t & u \\ \end{bmatrix} |
colspan="2"| A payoff matrix converted from A and B where player 1 has two possible actions V and W and player 2 has actions X, Y and Z |
In game theory, a bimatrix game is a simultaneous game for two players in which each player has a finite number of possible actions. The name comes from the fact that the normal form of such a game can be described by two matrices - matrix describing the payoffs of player 1 and matrix describing the payoffs of player 2.{{cite web | url=http://www.utdallas.edu/~chandra/documents/6311/bimatrix.pdf | title=Bimatrix games | accessdate=17 December 2015 | author=Chandrasekaran, R}}
Player 1 is often called the "row player" and player 2 the "column player". If player 1 has possible actions and player 2 has possible actions, then each of the two matrices has rows by columns. When the row player selects the -th action and the column player selects the -th action, the payoff to the row player is and the payoff to the column player is .
The players can also play mixed strategies. A mixed strategy for the row player is a non-negative vector of length such that: . Similarly, a mixed strategy for the column player is a non-negative vector of length such that: . When the players play mixed strategies with vectors and , the expected payoff of the row player is: and of the column player: .
Nash equilibrium in bimatrix games
Every bimatrix game has a Nash equilibrium in (possibly) mixed strategies. Finding such a Nash equilibrium is a special case of the Linear complementarity problem and can be done in finite time by the Lemke–Howson algorithm.
There is a reduction from the problem of finding a Nash equilibrium in a bimatrix game to the problem of finding a competitive equilibrium in an economy with Leontief utilities.{{Cite book|doi=10.1145/1109557.1109629|chapter=Leontief economies encode nonzero sum two-player games|title=Proceedings of the seventeenth annual ACM-SIAM symposium on Discrete algorithm - SODA '06|pages=659|year=2006|last1=Codenotti|first1=Bruno|last2=Saberi|first2=Amin|last3=Varadarajan|first3=Kasturi|last4=Ye|first4=Yinyu|isbn=0898716055}}
Related terms
A zero-sum game is a special case of a bimatrix game in which .
References
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