After considering lines of equal objective function value (the contour lines or topographical lines in figure 2.2 on page 18), why is necessary that a linear model will have either a single maximum point (global optimum) or an infinite number of optimal points? In what situations would we have an infinite number of solutions? Could we ever have a finite (and greater than 1) number of globally optimal points (all with the same objective function value)? That is, could we have 2, or 10, or 1000 globally optimal points with a linear model? Why?