Econometrica: Mar, 2006, Volume 74, Issue 2

Hard‐to‐Solve Bimatrix Games

https://doi.org/10.1111/j.1468-0262.2006.00667.x
p. 397-429

Rahul Savani, Bernhard Stengel

The Lemke–Howson algorithm is the classical method for finding one Nash equilibrium of a bimatrix game. This paper presents a class of square bimatrix games for which this algorithm takes, even in the best case, an exponential number of steps in the dimension of the game. Using polytope theory, the games are constructed using pairs of dual cyclic polytopes with 2 suitably labeled facets in ‐space. The construction is extended to nonsquare games where, in addition to exponentially long Lemke–Howson computations, finding an equilibrium by support enumeration takes on average exponential time.