D. Integer Programming
D.1.1. What Is Integer Programming?
In the prior chapters on linear programming (LP), the values of the decision variables were allowed to be any real number, which can include fractional or decimal values. Integer programming (IP), which can also be called integer linear programming, is a special case of LP in which the values of the n (number of) decision variables must be integers (0, 1, 2, and so on). This means that the formulation of the IP problem/model differs from the regular LP problem/model only in regard to the statement of the given requirements of the resulting solution. That is, we change the nonnegativity and given requirements from a set of real numbers:
and X1, X2, . . . , Xn