Solving Discrete Zero Point Problems with Vector Labeling

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 Z to the n-dimensional Euclidean space IR. Under two different boundary conditions, we give a constructive proof using a combinatorial argument based on a simplicial algorithm with vector labeling and lexicographic linear programming pivot steps. We also adapt the algorithm to prove the existence of a solution to the discrete complementarity problem.