With the addition of a new plant, Monsanto9 now has more capacity than it needs to manufacture its main chemical product. Numerous reactors i = 1,

c, m can be operated at a variety j = 1,

c, n of discrete combinations of settings for feed rate, reactor velocity, and reactor pressure. Both the production yield pi,j and the operating cost ci,j vary with reactor and setting.

Formulate an ILP model to find the least cost way to fulfill total production target b in terms of the decision variables 1i = 1,

c, m; j = 1,

c, n2 xi,j ! e 1 if reactor i operates at setting j 0 otherwise