Game theory -  A Tutorial

Static: General Results

Here are some of the key results of the theory of static games.

Theorem 1 (John Nash) [3]

A finite static game always has at least one Nash equilibrium, possibly mixed.

A finite game is one with finitely many players who all have a finite number of possible choices.  The proof of the result uses Kakutani’s fixed point theorem. 

 

Theorem 2 (Rosen) [4]

A concave static game always has at least one pure Nash equilibrium.

A convex  game is one where the players choose a sub-vector  xi of a vector x (that is some of the components of x) so that the resulting vector x  is in a convex set. Moreover, the payoff of player i is continuous in x and concave in xi.

John Nash