05_Duality Flashcards
1
Q
What is the Shadow price of a constraint in an LP?
What are alternative names?
A
- change in the optimal value of the objective function per unit increase in RHS (ceteris paribus)
- Dual variable, opportunity cost
2
Q
Shadow Prices
Denoted?
A
y with dash
3
Q
Reduced Costs
Denoted?
A
c with dash
4
Q
What is the Reduced Cost of a NBV in an LP
A
- change in optimal value when replacing one of the optimal products with another
- **increasing NBV **from 0 to 1
5
Q
Shadow Price
Simple Definition
A
- change in optimal value per unit increase in RHS
- ‘price for one addition unit of capacity’
- opportunity cost
6
Q
A
7
Q
When can you apply the Dual Simplex Method?
A
- LP needs to be dual feasible
- Dual Program has to be in canonical form
- that is the case if all coefficients of objective function of all NBVs are smaller or equal 0
8
Q
When can you use the dual simplex when primal is not in canonical form?
A
- if all coefficients of NBVs ≤ 0
- and **at least 1 RHS is negative **
9
Q
Primal infeasibility
corresponds to…
A
- e.g. b(i) < 0
- Primal infeasibility corresponds to feasible but not optimal dual solution
10
Q
A
