A note on reducing the number of variables in Integer Programming problems

A necessary and sufficient condition for identification of dominated columns, which correspond to one type of redundant integer variables, in the matrix of a general Integer Programming problem, is derived. The given condition extends our recent work on eliminating dominated integer variables in Knapsack problems, and revises a recently published procedure for reducing the number of variables in general Integer Programming problems given in the literature. A report on computational experiments for one class of large scale Knapsack problems, illustrating the function of this approach, is included.