Regarding linear programming, which of the following statements are correct?

1. A formulation for a linear programming model consists of a decision variable, a constraint and several objectives

2. Operations managers find very few types of LP models applicable today because finding an optimal solution is no longer a concern

3. The formulation for a linear programming problem cannot include more than one decision variable

4. The objective function is a linear relationship that either minimizes or maximizes value

5. When the numbers in the payoff table are revenues/sales/profits, the decision criterion maximin is equivalent to have alpha coefficient as 1 in Hurwicz Criterion.

Please list which statements are correct.