Network Simplex - Evaluating a Nonbasic Arc Previous Next
Suppose arc BC with flow  is added to the feasible spanning tree. The above network shows next to each arc the resulting incremental flow (in parentheses) and the cost per unit flow (to the left of the parentheses).
When , the resulting overall increment in total cost () is
  = 2(1) + 3(1) + 4(-1) + 3(-1) = -2.
Hence, the rate of change of  as  is increased is -2.