Fill in the blank:
1. In a problem involving capital budgeting applications, the 0-1 variables designate the _______ or _______ of the different projects.
2. If exactly one investment is to be selected from a set of five investment options, then the constraint is often called a ______ constraint.
3. If we are solving a 0-1 integer programming problem, the constraint x1 + x2 <= (less than equal to) 1 is a ______constraint.
4. If we are solving a 0-1 integer programming problem, the constraint x1 <= (less than equal to) x2 is a ______ constraint.
5. If we are solving a 0-1 integer programming problem, the constraint x1 = x2 is a ________constraint.