The goal of this paper is twofold. Firstly a short proof of the unicit
y of the reduced form of a normal form game is provided, using a techn
ique to reduce a game originally introduced by Mertens. Secondly a dir
ect combinatorial-geometric interpretation of the reduced form is desc
ribed. This description is then used to derive an algorithm for the ca
lculation of the reduced form of a game. (C) 1998 Elsevier Science B.V
.