The objective function always includes all of the decision v

The objective function always includes all of the decision variables, but that is not necessarily true of the constraints. Explain the difference between the objective function and the constraints. Then, explain why a constraint need not refer to all the variables.

Solution

Objective function   The part of a mathematical model such as a linear programming model that expresses what needs to be maximized or minimized, depending on the objective for the problem.

Constraint   A restriction on the feasible values of the decision variables.

a constraint need not refer to all the variables because depending on the restrictions, the feasible value of the variables are found and these variable values are used in the objective function to maximise or minimise.