SCM 460 Review

How could a network be modified if demand exceeds supply? Add extra Supply arcs Remove the extra demand arcs Add a dummy supply Add a dummy demand

Add a dummy supply node (The capacity you put it as has to be at least the difference between total supply and total demand to balance)

Decision variables in network flow problems are represented by nodes arcs demands supplies

Arcs

In a transshipment problem, which of the following statements is a correct representation of the balance-of-flow rule if Total supply < total demand Inflow-Outflow >= S or D I + O >= S or D I - O <= S or D I + O <= S or D

I - O <= S or D

What is the interpretation of units "shipped" along arcs from dummy supply nodes o demand nodes? Indicates unmet demand at demand nodes Indicates unmet supply at demand at supply nodes Indicates unmet supply at supply nodes

Indicates unmet demand at demand nodes

One approach to solving integer programming problems is to ignore the integral conditions and solve the problem with continuous decisions variables. This is refereed to as: quickest solution method LP satisficing LP relaxation LP approximation

LP relaxation (Always the best possible solution you can get)

The street intersections in a city road network represent Nodes Arcs Resources Expenses

Nodes

A factory which ships items through the network would be represented by which type of node? Demand Supply Random Decision

Supply

The objective function value for the ILP problem can never be as good as the optimal solution to its LP relaxation be as poor as the optimal solution to its LP relaxation be worse than the optimal solution to its LP relaxation be better than the optimal solution to its LP relaxation

be better than the optimal solution to its LP relaxation

If a company produces Product 1, then it must produce at least 150 units of Product 1. Which of the following constraints enforces this condition. x1<= 150Y1 x1 - 150Y1 >=0 x1Y1 <=150 x1>= 150+Y1 Y1 = whether or not to produce product 1 (Binary variable meaning value can only be 1 or 0) x1 is number of units to be produced of product 1

x1 - 150Y1 >= 0 (because you cant have a variable on the right hand side)

A company want to select no more than 2 projects from a set of 4 possible projects. Which of the following constraints ensure that no more than 2 will be selected? x1+x2+x3+x4 = 2 x1+x2+x3+x4<= 2 x1+x2+x3+x4>=2 x1+x2+x3+x4>=0 (These are binary variables because it is whether it is chosen or not so if picked = 1 if not = 0 and they only want to of the four)

x1+x2+x3+x4 <= 2