Greater than x or greater than x3, like that. and then we're going to have a fourth inequality. that says that it has to be less than or equal to the sum of those three. so what this construction does is if the equation is satisfied, if there's some way to satisfy this equation then it's going to be C1 equals to one. so that is, if there is a way to, make each one of these terms one, say by setting X1 to zero, X2 to one and X3 to one, then this thing will be, those things all will be true. and then this one also will be true. 