A Short Course in Linear Programming
Lesson 6. Mathematics of LP
First, look at Theorems of the alternative
in my glossary (pay special attention to those of Fourier, Farkas and Motzkin).
Second, read The Fundamental
Theorems of Linear Programming, and see if you can prove them.
Third, look up the following terms in my glossary:
Exercises. Let
be a finite collection of m inequalities, and let M ={1,...,m}.
Define the dual system: .
The support set, ,
of a non-negative vector, v, is the set of indexes for which
the coordinate is positive. In particular,
is the support set for y satisfying the dual system, and
is the set of rows with surplus for a solution, x, to S.
Prove each of the following.
-
x and y must satisfy complementary slackness: .
Solution.
-
If both S and are
consistent, there must exist a strictly complementary solution:
such that .
Solution.
-
If and
are two strictly complementary solutions to S and ,
their partitions are the same: .
Solution.
-
S is inconsistent if, and only if,
is consistent. Further, let Y =
{y: y satisfies Sd and yb
> 0}, and suppose .
Then,
is an IIS if, and only if, there does not exist
such that .
(In the latter, such a y is called an elementary vector
of Y.)
Solution.
-
Suppose S is consistent. Then,
is redundant in S if, and only if,
is consistent. This is strongly redundant if, in addition, yb
> 0.
Solution.
-
Suppose S is consistent. Then,
is an implied equality of S if, and only if,
is consistent.
Solution.
Last updated: March 24, 1997