This discussion paper resulted in a publication in the 'SIAM Journal on Optimization', 2007, 18, 290-308. <P> In this paper we present two general results on the existence of a discrete zero point of a function from the n-dimensional integer lattice Zn to the n-dimensional Euclidean space Rn. Under...</p>

Any function from a non-empty polytope into itself that is locally gross direction preserving is shown to have the fixed point property. Brouwer's fixed point theorem for continuous functions is a special case. We discuss the application of the result in the area of non-cooperative game...</p>

In this paper we present two general results on the existence of a discrete zero point of a function from the <I>n</I>-dimensional integer lattice Z<SUP><I>n</SUP></I> to the <I>n</I>-dimensional Euclidean space R<SUP><I>n</SUP></I>. Under two different boundary conditions, we give a constructive proof using a combinatorial argument based on a...</i></sup></i></i></sup></i>

Any function from a non-empty polytope into itself that is locally gross direction preserving is shown to have the fixed point property. Brouwer's fixed point theorem for continuous functions is a special case. We discuss the application of the result in the area of non-cooperative game theory.