“…In the corresponding PAproblem, we have arcs (x; y) 1 and (z; x) 1 with (cost, lower, upper) = (-1,0,1), arc (y; z) 1 with (cost, lower, upper) = (-1,0,3), arcs (x; y) 2 , (y; z) 2 , and (z; x) 2 with (cost, lower, upper) = (0,0,1), and arcs (x; y) 3 , (y; z) 3 , and (z; x) 3 with (cost,lower,upper) = (1; 0; 1). Then, we get a feasible ow by assigning ow of 1 unit on arcs (x; y) 1 , (x; y) 2 , (z; x) 1 , and (z; x) 2 , and 2 units on (y; z) 1 . The total cost is -4, which is minimum.…”