Function-Variable Incidence Matrix x y a) f(il,i2) jlj2 J4j3 g(il,i2) jlj3 jlJ3 Index Definitions i,: L = 1 U=3 A = 1 Jl: L = 1 U = ii A= J4: L = 1 U = U. ii- i: L = l j2: i2-1 FIGURE 2-2 AN EXA:''LE PROBLEM U=2 A= i3: i2 i2+1