L6 - Graphical Solutions

Question 1

What is a isovalue line?

Answer 1

a family of parallel straight lines representing
different values of the objective function – these
are called isovalue lines (the same value lines).

Question 2

What is a polyhedral set?

Answer 2

• if a feasible region of an LP is a poly hedreal set
• it has an optimal solution found at a corner
• but the optimal solution is not unique
• can happen at two corners or anywhere inbetween

Question 3

When is a linear program infeasible?

Answer 3

if it has no feasible solution ( and therefore no optimal solution)
- this means the constraints are inconsistent

Question 4

What happens with unbounded objective function?

Answer 4

the opjective function may go to infinity over the feasible region.
- This usually indicates a mistake in the mode specification

Question 5

When is graphical solutions not optimal for solving linear programming?

Answer 5

• when you have more than two variables

- it can be done with 3 variables on a 3 dimensional graph but this is hard to do and interpret