
Duality and Sensitivity Analysis in Linear Programming 311
12.2. Write down the dual of the LP formulated for the diet problem in Ex-
ample 10.2 (page 213). Provide an economic interpretation of the dual
LP.
12.3. Prove or disprove each of the following statements concerning a primal
LP,
maximize z = c
T
x subject to Ax ≤ b, x ≥ 0
and the corresponding dual LP,
minimize w = b
T
y subject to A
T
y ≥ c, y ≥ 0.
(a) If the primal LP is infeasible, the corresponding dual LP must be
unbounded.
(b) If the primal LP has a nonempty, bounded feasible region, then the
corresponding dual LP must have a global minimum.
(c) If b<0, then the primal LP is infeasible.
(d) If