In the adapatation of the simplex algorithm for solving separable-programming problems in which variables are approximated by a set of grid variables, the restricted basis entry rule only allows, for each original variable, no more than two such neighboring grid variables to be in a solution. Such a rule is also used in solving quadratic-programming problems to force certain complementarity conditions to hold. Separable programming; Special ordered sets of type 2; Wolfe's quadratic programming-problem algorithm.