H5: The Theory of the Simplex Method

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5.1 Foundations of the Simplex Method

5.2 The Simplex Method in Matrix Form

5.3 A Fundamental Insight

After any iteration, the makeup of the tableau is as follows:

Row 0 = [ -c, 0, 0 ] + cbB-1[A, I, b]
Rows 1 to m = B-1[A, I, b]

Fundamental Insight

When B is the basis matrix for the optimal solution found, let

S* = B-1 = coefficients of the slack variables, rows 1 to m
A* = B-1A = coefficients of the original variables, rows 1 to m
y* = cbB-1 = coefficients of the slack variables in row 0
z* = cbB-1A, so z* - c = coefficients of the original variables in row 0
Z* = cbB-1B = optimal value of the objective function
b* = B-1B = optimal right-hand sides of rows 1 to m

Then the fundamental insight is:

1) t*  = t+y*T = [ y*A-c | y*y*b ]
2) T* = S*T = [ S*AS* | S*b  ]

Example

Initial Tableau

Row 0:

Other rows:

Combined:

Final Tableau

Row 0:

Other rows:

Combined:

Adapting to Other Model Forms

Applications

The fundamental insight reveals that Z* is

 

 

5.4 The Revised Simplex Method

 

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