Explore tens of thousands of sets crafted by our community.
Transportation and Assignment Models
10
Flashcards
0/10
The Transportation Problem
The transportation problem seeks to minimize the cost of distributing a product from several sources to various destinations. Differences: It is a type of linear programming problem; different from general LP due to its structure. Similarities: Uses LP simplex or modified simplex method for solution. Solution approaches: The Northwest Corner Method, The Minimum Cost Method, The Vogel Approximation Method.
Linear Programming Solution to Transportation Problems
Linear programming (LP) can be used to solve transportation problems with a more mathematical and optimal approach. Differences: LP solutions are optimal, not heuristic. Similarities: All methods ultimately use LP formulations for optimality. Solution approaches: Formulate the problem as an LP, apply the simplex or modified simplex methods, iterate to find the optimal solution.
The Hungarian Method for Assignment Problems
The Hungarian Method finds the optimal solution for assignment problems. Differences: It is a combinatorial optimization algorithm specific to assignment problems. Similarities: Related to other matrix minimization methods in LP. Solution approaches: Subtract row and column minima, cover all zeros with a minimum number of lines, adjust the uncovered numbers, and repeat until an optimal assignment is found.
The Vogel Approximation Method (VAM)
VAM is a heuristic used to find a good initial solution to the transportation problem by minimizing penalties. Differences: It considers penalties for not choosing the next best cell. Similarities: Also a method for finding an initial feasible solution. Solution approaches: Calculate penalties, choose the highest penalty cell, allocate as much as possible, adjust remaining supply and demand, repeat until all needs are satisfied.
The Northwest Corner Method
The Northwest Corner Method is a heuristic for finding an initial feasible solution to the transportation problem. Differences: It does not guarantee the optimal solution. Solutions are found at the 'northwest corner' of the matrix. Similarities: It's a stepping stone to move towards optimality using other methods. Solution approaches: Selecting the northwest-most cell, allocating as much as possible, and moving south or east in the matrix.
Balanced vs Unbalanced Transportation Problems
Balanced transportation problems have total supply equal to total demand, while unbalanced ones need additional dummy rows or columns. Differences: The need for dummy variables to balance the problem. Similarities: Both can be solved using similar methods. Solution approaches: Add dummy rows or columns with zero cost for unbalanced problems, then apply the standard transportation problem-solving methods.
The Assignment Problem
The assignment problem deals with finding a one-to-one matching between tasks and agents. Differences: It's a special case of the transportation problem with all supply and demand equal to 1. Similarities: Hungarian Method used is a special form of the dual-simplex method. Solution approaches: Hungarian Method, Linear Programming, Branch and Bound Technique.
Cycle Method in Transportation Problems
The cycle method is used in solving transportation problems by identifying cycles within the solution matrix to make adjustments towards optimality. Differences: It is used after an initial solution is found. Similarities: It helps improve upon the current solution, heading towards optimality. Solution approaches: Identify closed loops in the matrix, make adjustments to the allocation of the loop cells, and repeat until no improvements are found.
Sensitivity Analysis in Transportation and Assignment Problems
Sensitivity analysis examines the effect of changes in parameters on the optimal solution of transportation and assignment problems. Differences: Focuses on changes and their impacts, not on finding the initial solution. Similarities: Necessary for understanding the robustness of the solution. Solution approaches: Alter parameters like costs, supply, and demand, re-solve the problem and evaluate changes in the optimal solution and cost.
The Minimum Cost Method
The Minimum Cost Method is another initial feasible solution heuristic for transportation problems. Differences: Favors cells with the lowest cost, not position-based like Northwest Corner Method. Similarities: It is another starting point for optimization. Solution approaches: Find the minimum cost cell, allocate as much as possible, adjust supply and demand, and repeat until all are filled.
© Hypatia.Tech. 2024 All rights reserved.