the intact one

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Unbalanced Assignment Problems

Whenever the cost matrix of an assignment problem is not a square matrix, that is, whenever the number of sources is not equal to the number of destinations, the assignment problem is called an unbalanced assignment problem. In such problems, dummy rows (or columns) are added in the matrix so as to complete it to form a square matrix. The dummy rows or columns will contain all costs elements as zeroes. The Hungarian method may be used to solve the problem.

Example :  A company has five machines that are used for four jobs. Each job can be assigned to one and only one machine. The cost of each job on each machine is given in the following Table.

Unbalanced Maximization Assignment problem example

Assignment Problem

topic 5.1.png

Solution:  Convert the 4 × 5 matrix into a square matrix by adding a dummy row D5.

Dummy Row D5 Added

topic 5.2.png

Row-wise Reduction of the Matrix

topic 5.3.png

Column-wise reduction is not necessary since all columns contain a single zero. Now, draw minimum number of lines to cover all the zeros, as shown in Table.

All Zeros in the Matrix Covered

topic 5.4.png

Number of lines drawn ≠ Order of matrix. Hence not optimal.

Select the least uncovered element, i.e., 1, subtract it from other uncovered elements, add to the elements at intersection of lines and leave the elements that are covered with single line unchanged as shown in Table.

Subtracted or Added to Elements

topic 5.5.png

Again Added or Subtracted 1 from Elements

topic 5.6

Number of lines drawn = Order of matrix. Hence optimality is reached. Now assign the jobs to machines, as shown in Table.

Assigning Jobs to Machines

topic 5.7.png

Example :  In a plant layout, four different machines M1, M2, M3 and M4 are to be erected in a machine shop. There are five vacant areas A, B, C, D and E. Because of limited space, Machine M2 cannot be erected at area C and Machine M4 cannot be erected at area A. The cost of erection of machines is given in the Table.

topic 5.9.png

Find the optimal assignment plan.

Solution:  As the given matrix is not balanced, add a dummy row D5 with zero cost values. Assign a high cost H for (M2, C) and (M4, A). While selecting the lowest cost element neglect the high cost assigned H, as shown in Table below.

topic 5.10

– Row-wise reduction of the matrix is shown in Table.

Matrix Reduced Row-wise

topic 5.11.png

Note:  Column-wise reduction is not necessary, as each column has at least one single zero. Now, draw minimum number of lines to cover all the zeros, see Table.

Lines Drawn to Cover all Zeros

topic 5.12.png

Number of lines drawn ≠ Order of matrix. Hence not Optimal. Select the smallest uncovered element, in this case 1. Subtract 1 from all other uncovered element and add 1 with the elements at the intersection. The element covered by single line remains unchanged. These changes are shown in Table. Now try to draw minimum number of lines to cover all the zeros.

Added or Subtracted 1 from Elements

topic 5.13.png

Now number of lines drawn = Order of matrix, hence optimality is reached. Optimal assignment of machines to areas are shown in Table.

Optimal Assignment

topic 5.14.png

Hence, the optimal solution is:

topic 5.15.png

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Linear assignment with non-perfect matching

Dec 8, 2020

The linear assignment problem (or simply assignment problem) is the problem of finding a matching between two sets that minimizes the sum of pair-wise assignment costs. This can be expressed as finding a matching (or independent edge set) in a bipartite graph \(G = (U, V, E)\) that minimizes the sum of edge weights. The edge weights may be positive or negative and the bipartite graph does not need to be complete : if there is no edge between two vertices then they cannot be associated. Note that a maximum-weight assignment can be obtained by negating the weights and finding a minimum-weight assignment.

The simplest form of the assignment problem assumes that the bipartite graph is balanced (the two sets of vertices are the same size) and that there exists a perfect matching (in which every vertex has a match). Let \(n\) be the number of elements in each set and let \(C\) be a square matrix of size \(n \times n\) that contains the edge weights. Missing edges are represented by \(\infty\), such that \(C_{i j} < \infty \Leftrightarrow (i, j) \in E\). The assignment problem can then be clearly expressed as an integer linear program : (note that the problem is not actually solved using a general-purpose ILP solver, it is just a convenient framework in which to express the problem)

The constraint that the sum of each row and column is equal to one ensures that each element has exactly one match. However, what happens when the graph is not balanced or does not contain a perfect matching? We cannot enforce the sums to be equal to one. Which problem should be solved?

I recommend reading the tech report “On Minimum-Cost Assignments in Unbalanced Bipartite Graphs” by Lyle Ramshaw and Robert E. Tarjan. I will summarize some of the main points here.

Let us consider a more general, rectangular problem of size \(r \times n\) and assume (without loss of generality) that \(r \le n\). If \(r = n\) then the problem is balanced, if \(r < n\) it is unbalanced.

Clearly an unbalanced probem cannot have a perfect matching, since there will be at least \(n - r\) unmatched elements in the larger set. However, it may be possible to find a matching in which every vertex in the smaller set has a match. This is referred to as a one-sided perfect matching and the optimization problem can be expressed:

The inequality constraints enforce that each element in the smaller set has exactly one match while each element in the larger set has at most one match. Ramshaw and Tarjan outline a method to reduce from an unbalanced problem to a balanced problem while preserving sparsity. A simple alternative is to add \(n - r\) rows of zeros and then exclude these edges from the eventual solution. Most libraries for the assignment problem solve either the balanced or unbalanced version of this problem (see the later section).

However, whether balanced or unbalanced, it may still occur that the constraint set is infeasible, meaning that there does not exist a (one-sided) perfect matching. Let \(\nu(W) \le r\) denote the size of the largest matching in the graph. If \(\nu(W) < r\), then there does not exist a one-sided perfect matching and all possible matchings are imperfect.

Ramshaw and Tarjan actually outline three different versions of the assignment problem:

  • perfect matching
  • imperfect matching
  • minimum-weight matching

The imperfect matching problem is to find the matching of size \(\nu(G)\) with the minimum cost. The minimum-weight matching problem is to find the matching of any size with the minimum cost. If \(\nu(G) = r = n\), then perfect and imperfect matching coincide. Otherwise, when \(\nu(G) < n\), there does not exist a perfect matching.

The imperfect matching problem can be expressed

and the minimum-weight matching problem can be expressed

Ramshaw and Tarjan show that both of these problems can be reduced to finding a perfect matching in a balanced graph. When using linear assignment, we should carefully consider which of the three problems we actually want to solve.

In support of minimum-weight matching

The minimum-weight matching problem is often the most natural choice, since it puts no constraint on the size of the matching. To illustrate the difference between this and the other problems, consider the following balanced problem:

The solution to perfect (or imperfect) matching is to choose -1 and -2 for a total score of -3 and a cardinality of 2. The solution to minimum-weight matching is to choose -4 with a cardinality of 1.

Minimum-weight matching will never select an edge with positive cost: it is better to simply leave it unselected. Edges with zero cost have no impact.

It may be more natural to consider the maximization of positive weights than the minimization of negative costs.

Min-cost imperfect matching with positive weights

Be careful when solving imperfect matching problems with positive edge weights! I would avoid this situation altogether due to the tension that exists between maximizing the number of matches and minimizing the sum of (positive) costs. This may result in the unexpected behaviour that adding an edge to the graph increases the minimum cost. For example, compare the following two problems:

Quick and dirty transformations

Ramshaw and Tarjan above describes some clever techniques to transform imperfect and minimum-weight matching problems into perfect matching problems while preserving sparsity. Here we describe some quick and dirty alternatives.

We can always transform an unbalanced (and therefore imperfect) problem into a balanced problem by adding \(n - r\) rows of zeros. The resulting balanced graph has a perfect matching if and only if the original unbalanced graph had a matching of size \(r\) (in which every vertex in the smaller set is matched).

If we need to solve imperfect matching but we only have a solver for perfect matching, it suffices to replace the infinite edge weights with a large, finite cost (e.g. larger than the total absolute value of all weights). The resulting graph must contain a perfect matching since it is a complete bipartite graph, and each high-cost edge is worth more than all original edges combined. The high-cost edges can be excluded at the end.

Most existing packages either solve perfect, one-sided perfect or imperfect matching. To use one of these solvers for the minimum-weight matching problem, it suffices to replace all positive edges (including infinite edges) with zero. If using a solver that leverages sparsity, it is better to use the technique described by Ramshaw and Tarjan.

Python packages

The table below outlines the different behaviour of several popular packages. The code that was used to determine the behaviour is available as a Jupyter notebook .

Module Function Behaviour
Requires that problem is balanced (or else raises an exception). Requires that a perfect matching exists (or else returns infinite cost).
Supports unbalanced problems (with ; although check issues , ). Requires that a one-sided perfect matching exists (or else returns infinite cost).
Supports unbalanced problems. Requires that a one-sided perfect matching exists (or else raises an exception).
Supports unbalanced problems. Supports imperfect matching.
Requires problem is balanced. Requires that a perfect matching exists (or else raises an exception). Requires that costs are integer-valued.

Quantitative Techniques: Theory and Problems by P. C. Tulsian, Vishal Pandey

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UNBALANCED ASSIGNMENT PROBLEM

Unbalanced Assignment problem is an assignment problem where the number of facilities is not equal to the number of jobs. To make unbalanced assignment problem, a balanced one, a dummy facility(s) or a dummy job(s) (as the case may be) is introduced with zero cost or time.

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unbalanced assignment problem meaning

Unbalanced Assignment Problem

In the previous section, the number of persons and the number of jobs were assumed to be the same. In this section, we remove this assumption and consider a situation where the number of persons is not equal to the number of jobs . In all such cases, fictitious rows and/or columns are added in the matrix to make it a square matrix.

  • Maximization Problem
  • Multiple Optimal Solutions

Example: Unbalanced Assignment Problem

Job
Person 1 2 3 4
A 20 25 22 28
B 15 18 23 17
C 19 17 21 24

Since the number of persons is less than the number of jobs, we introduce a dummy person (D) with zero values. The revised assignment problem is given below:

Use Horizontal Scrollbar to View Full Table Calculation.

Job
Person 1 2 3 4
A 20 25 22 28
B 15 18 23 17
C 19 17 21 24
D (dummy) 0 0 0 0

Now use the Hungarian method to obtain the optimal solution yourself. Ans. = 20 + 17 + 17 + 0 = 54.

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Assignment Problem: Meaning, Methods and Variations | Operations Research

unbalanced assignment problem meaning

After reading this article you will learn about:- 1. Meaning of Assignment Problem 2. Definition of Assignment Problem 3. Mathematical Formulation 4. Hungarian Method 5. Variations.

Meaning of Assignment Problem:

An assignment problem is a particular case of transportation problem where the objective is to assign a number of resources to an equal number of activities so as to minimise total cost or maximize total profit of allocation.

The problem of assignment arises because available resources such as men, machines etc. have varying degrees of efficiency for performing different activities, therefore, cost, profit or loss of performing the different activities is different.

Thus, the problem is “How should the assignments be made so as to optimize the given objective”. Some of the problem where the assignment technique may be useful are assignment of workers to machines, salesman to different sales areas.

Definition of Assignment Problem:

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Suppose there are n jobs to be performed and n persons are available for doing these jobs. Assume that each person can do each job at a term, though with varying degree of efficiency, let c ij be the cost if the i-th person is assigned to the j-th job. The problem is to find an assignment (which job should be assigned to which person one on-one basis) So that the total cost of performing all jobs is minimum, problem of this kind are known as assignment problem.

The assignment problem can be stated in the form of n x n cost matrix C real members as given in the following table:

unbalanced assignment problem meaning

  • DOI: 10.4236/AJOR.2016.64028
  • Corpus ID: 124980289

Solving the Unbalanced Assignment Problem: Simpler Is Better

  • Nathan K. Betts , Francis J. Vasko
  • Published 24 June 2016
  • Mathematics
  • American Journal of Operations Research

Tables from this paper

table 1

8 Citations

An amalgamated approach for solving unbalanced assignment problem, modified hungarian method for unbalanced assignment problem with multiple jobs, modified hungarian method for solving balanced fuzzy transportation problems.

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Solving the Unbalanced Assignment Problem: Simpler Is Better

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American Journal of Operations Research

Related Papers

Dr Avanish Kumar

unbalanced assignment problem meaning

Bhausaheb G Kore

In this paper I have proposed a new approach to solve an unbalanced assignment problem (UBAP). This approach includes two parts. First is to obtain an initial basic feasible solution (IBFS) and second part is to test optimality of an IBFS. I have proposed two new methods Row Penalty Assignment Method (RPAM) and Column Penalty Assignment Method (CPAM) to obtain an IBFS of an UBAP. Also I have proposed a new method Non-basic Smallest Effectiveness Method (NBSEM) to test optimality of an IBFS. We can solve an assignment problem of maximization type using this new approach in opposite sense. By this new approach, we achieve the goal with less number of computations and steps. Further we illustrate the new approach by suitable examples. INTRODUCTION The assignment problem is a special case of the transportation problem where the resources are being allocated to the activities on a one-to-one basis. Thus, each resource (e.g. an employee, machine or time slot) is to be assigned uniquely to a particular activity (e.g. a task, site or event). In assignment problems, supply in each row represents the availability of a resource such as a man, machine, vehicle, product, salesman, etc. and demand in each column represents different activities to be performed such as jobs, routes, factories, areas, etc. for each of which only one man or vehicle or product or salesman respectively is required. Entries in the square being costs, times or distances. The assignment method is a special linear programming technique for solving problems like choosing the right man for the right job when more than one choice is possible and when each man can perform all of the jobs. The ultimate objective is to assign a number of tasks to an equal number of facilities at minimum cost (or maximum profit) or some other specific goal. Let there be 'm' resources and 'n' activities. Let c ij be the effectiveness (in terms of cost, profit, time, etc.) of assigning resource i to activity j (i = 1, 2, …., m; j = 1, 2,…., n). Let x ij = 0, if resource i is not assigned to activity j and x ij = 1, if resource i is assigned to activity j. Then the objective is to determine x ij 's that will optimize the total effectiveness (Z) satisfying all the resource constraints and activity constraints. 1. Mathematical Formulation Let number of rows = m and number of columns = n. If m = n then an AP is said to be BAP otherwise it is said to be UBAP. A) Case 1: If m < n then mathematically the UBAP can be stated as follows:

Malaya Journal of Matematik

DR ANJU KHANDELWAL

International Journal for Research in Applied Science & Engineering Technology (IJRASET)

IJRASET Publication

In this paper a new method is proposed for finding an optimal solution of a wide range of assignment problems, directly. A numerical illustration is established and the optimality of the result yielded by this method is also checked. The most attractive feature of this method is that it requires very simple arithmetical and logical calculations. The method is illustrated through an example.

Hussein Ali Hussein Al-Dallal Al-Saeedi

archana pandey

Assignment problems arise in different situation where we have to find an optimal way to assign n-objects to mother objects in an injective fashion. The assignment problems are a well studied topic in combinatorial optimization. These problems find numerous application in production planning, telecommunication VLSI design, economic etc. The assignment problems is a special case of Transportation problem. Depending on the objective we want to optimize, we obtain the typical assignment problems. Assignment problem is an important subject discussed in real physical world we endeavor in this paper to introduce a new approach to assignment problem namely, matrix ones assignment method or MOA-method for solving wide range of problem. An example using matrix ones assignment methods and the existing Hungarian method have been solved and compared it graphically. Also some of the variations and some special cases in assignment problem and its applications have been discussed in the paper.

Sultana Rafi

The assignment problem is a particular type of linear programming problem. In this paper, we analyzed the standard and existing proposed methods. After studying these methods, we proposed a new alternative method for solving the assignment problem. We examined the newly proposed method by a couple of numerical examples and compare this result with the standard method. The main characteristic of this newly proposed method is that it constructed a very easy logical and arithmetical algorithm. Here we point out some advantages and limitations of the new proposed method. Programming code for the newly proposed method has been added in this paper.

Ranjan Kumar Mondal

Thecloudcomputingpresentsatypeofassignmentsandsystemswhichoccupydistributedresources toexecutearoleinadistributedway.Cloudcomputingmakeuseoftheonlinesystemsonthewebto assisttheimplementationofcomplicatedassignments;thatneedhuge-scalecomputation.Itwassaid withtheintentionofinourlivingworld;wecanfinditchallengingtobalanceworkloadsofcloud computingamongassignments(jobsortasks)andsystems(machinesornodes),sothemajorityofthe timewehavetopromoteaconditiontounbalancedassignmentproblems(unequaltaskallocations). The present article submits a new technique to solve the unequal task allocation problems. The techniqueisofferedinanalgorithmicmodelandputintopracticeontheseveralgroupsofinputto investigatethepresentationandusefulnessoftheworks.Anevaluationispreparedwiththepresented approach.Itmakessurethattheproposedapproachprovidesabetteroutcomebycomparingwith someotherexistingalgorithms.

Industrial Engineering Journal

Shridhar Mhalsekar

Journal of Advances in Mathematics and Computer Science

Hudu Mohammed

Assignment problem is an important area in Operation Research and is also discussed in real physical world. In this paper an attempt has been made to solve the assignment problem using a new Method called the Penalty method. We discuss a numerical example by using the new Method and compare it with standard existing method which is the Hungarian method. We compare the optimal solution of the new Method and the Hungarian method. The new method is a simple procedure, easy to apply for solving assignment problem.

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unbalanced assignment problem meaning



> > Assignment Problem example (Using Hungarian method)
( ) )



4. Unbalanced Assignment Problem

\ IIIIIIIV
A9141915
B7172019
C9182118
D10121819
E10152116
   `I`  `II`  `III`  `IV`    
 `A` 
 `B` 
 `C` 
 `D` 
 `E` 
   
   `I`  `II`  `III`  `IV`  `J_5`    
 `A` 
 `B` 
 `C` 
 `D` 
 `E` 
   
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   `9=9-0`  `14=14-0`  `19=19-0`  `15=15-0`  `0=0-0`  Minimum element of `1^(st)` row
 `B`   `7=7-0`  `17=17-0`  `20=20-0`  `19=19-0`  `0=0-0`  Minimum element of `2^(nd)` row
 `C`   `9=9-0`  `18=18-0`  `21=21-0`  `18=18-0`  `0=0-0`  Minimum element of `3^(rd)` row
 `D`   `10=10-0`  `12=12-0`  `18=18-0`  `19=19-0`  `0=0-0`  Minimum element of `4^(th)` row
 `E`   `10=10-0`  `15=15-0`  `21=21-0`  `16=16-0`  `0=0-0`  Minimum element of `5^(th)` row
   
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   `2=9-7`  `2=14-12`  `1=19-18`  `0=15-15`  `0=0-0`
 `B`   `0=7-7`  `5=17-12`  `2=20-18`  `4=19-15`  `0=0-0`
 `C`   `2=9-7`  `6=18-12`  `3=21-18`  `3=18-15`  `0=0-0`
 `D`   `3=10-7`  `0=12-12`  `0=18-18`  `4=19-15`  `0=0-0`
 `E`   `3=10-7`  `3=15-12`  `3=21-18`  `1=16-15`  `0=0-0`
     Minimum element of `1^(st)` column  Minimum element of `2^(nd)` column  Minimum element of `3^(rd)` column  Minimum element of `4^(th)` column  Minimum element of `5^(th)` column
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   (4) Columnwise cell `(A,IV)` is assigned  Columnwise `(A,J_5)` crossed off because
(1) Rowwise cell `(C,J_5)` is assigned
 `B`   (2) Columnwise cell `(B,I)` is assigned  Columnwise `(B,J_5)` crossed off because
(1) Rowwise cell `(C,J_5)` is assigned
 `C`   (1) Rowwise cell `(C,J_5)` is assigned
so columnwise cell `(A,J_5)`,`(B,J_5)`,`(D,J_5)`,`(E,J_5)` crossed off.
 `D`   (3) Columnwise cell `(D,II)` is assigned
so rowwise cell `(D,III)` crossed off.
 Rowwise `(D,III)` crossed off because
(3) Columnwise cell `(D,II)` is assigned
 Columnwise `(D,J_5)` crossed off because
(1) Rowwise cell `(C,J_5)` is assigned
 `E`   Columnwise `(E,J_5)` crossed off because
(1) Rowwise cell `(C,J_5)` is assigned
   
   `I`  `II`  `III`  `IV`  `J_5`    
 `A` 
 `B` 
 `C`   (3) Mark(✓) row `C` since column `J_5` has an assignment in this row `C`.
 `D` 
 `E`   (1) Mark(✓) row `E` since it has no assignment
     (2) Mark(✓) column `J_5` since row `E` has 0 in this column
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   cell covered by a line  cell covered by a line  cell covered by a line  cell covered by a line  `1=0+1`
intersection cell of two lines
 `B`   cell covered by a line  cell covered by a line  cell covered by a line  cell covered by a line  `1=0+1`
intersection cell of two lines
 `C`   `1=2-1`
cell not covered by a line
 `5=6-1`
cell not covered by a line
 `2=3-1`
cell not covered by a line
 `2=3-1`
cell not covered by a line
 cell covered by a line
 `D`   cell covered by a line  cell covered by a line  cell covered by a line  cell covered by a line  `1=0+1`
intersection cell of two lines
 `E`   `2=3-1`
cell not covered by a line
 `2=3-1`
cell not covered by a line
 `2=3-1`
cell not covered by a line
 `0=1-1`
cell not covered by a line
 cell covered by a line
   
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   (1) Rowwise cell `(A,IV)` is assigned
so columnwise cell `(E,IV)` crossed off.
 `B`   (2) Rowwise cell `(B,I)` is assigned
 `C`   (3) Rowwise cell `(C,J_5)` is assigned
so columnwise cell `(E,J_5)` crossed off.
 `D`   (4) Columnwise cell `(D,II)` is assigned
so rowwise cell `(D,III)` crossed off.
 Rowwise `(D,III)` crossed off because
(4) Columnwise cell `(D,II)` is assigned
 `E`   Columnwise `(E,IV)` crossed off because
(1) Rowwise cell `(A,IV)` is assigned
 Columnwise `(E,J_5)` crossed off because
(3) Rowwise cell `(C,J_5)` is assigned
   
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   (4) Mark(✓) row `A` since column `IV` has an assignment in this row `A`.
 `B` 
 `C`   (5) Mark(✓) row `C` since column `J_5` has an assignment in this row `C`.
 `D` 
 `E`   (1) Mark(✓) row `E` since it has no assignment
     (2) Mark(✓) column `IV` since row `E` has 0 in this column  (3) Mark(✓) column `J_5` since row `E` has 0 in this column
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   `1=2-1`
cell not covered by a line
 `1=2-1`
cell not covered by a line
 `0=1-1`
cell not covered by a line
 cell covered by a line  cell covered by a line
 `B`   cell covered by a line  cell covered by a line  cell covered by a line  `5=4+1`
intersection cell of two lines
 `2=1+1`
intersection cell of two lines
 `C`   `0=1-1`
cell not covered by a line
 `4=5-1`
cell not covered by a line
 `1=2-1`
cell not covered by a line
 cell covered by a line  cell covered by a line
 `D`   cell covered by a line  cell covered by a line  cell covered by a line  `5=4+1`
intersection cell of two lines
 `2=1+1`
intersection cell of two lines
 `E`   `1=2-1`
cell not covered by a line
 `1=2-1`
cell not covered by a line
 `1=2-1`
cell not covered by a line
 cell covered by a line  cell covered by a line
   
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   (5) Columnwise cell `(A,III)` is assigned  Columnwise `(A,IV)` crossed off because
(3) Rowwise cell `(E,IV)` is assigned
 `B`   (1) Rowwise cell `(B,I)` is assigned
so columnwise cell `(C,I)` crossed off.
 `C`   Columnwise `(C,I)` crossed off because
(1) Rowwise cell `(B,I)` is assigned
 (2) Rowwise cell `(C,J_5)` is assigned
so columnwise cell `(E,J_5)` crossed off.
 `D`   (4) Columnwise cell `(D,II)` is assigned
so rowwise cell `(D,III)` crossed off.
 Rowwise `(D,III)` crossed off because
(4) Columnwise cell `(D,II)` is assigned
 `E`   (3) Rowwise cell `(E,IV)` is assigned
so columnwise cell `(A,IV)` crossed off.
 Columnwise `(E,J_5)` crossed off because
(2) Rowwise cell `(C,J_5)` is assigned
   
   `I`  `II`  `III`  `IV`  `J_5`    
 `A`   Original cost 9  Original cost 14  Original cost 19  Original cost 15  Original cost 0
 `B`   Original cost 7  Original cost 17  Original cost 20  Original cost 19  Original cost 0
 `C`   Original cost 9  Original cost 18  Original cost 21  Original cost 18  Original cost 0
 `D`   Original cost 10  Original cost 12  Original cost 18  Original cost 19  Original cost 0
 `E`   Original cost 10  Original cost 15  Original cost 21  Original cost 16  Original cost 0
   
WorkJobCost
`A``III`
`B``I`
`C``J_5`
`D``II`
`E``IV`
Total54

unbalanced assignment problem meaning

unbalanced assignment problem meaning

Balanced and Unbalanced Transportation Problems

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The two categories of transportation problems are balanced and unbalanced transportation problems . As we all know, a transportation problem is a type of Linear Programming Problem (LPP) in which items are carried from a set of sources to a set of destinations based on the supply and demand of the sources and destinations, with the goal of minimizing the total transportation cost. It is also known as the Hitchcock problem.

Introduction to Balanced and Unbalanced Transportation Problems

Balanced transportation problem.

The problem is considered to be a balanced transportation problem when both supplies and demands are equal.

Unbalanced Transportation Problem

Unbalanced transportation problem is defined as a situation in which supply and demand are not equal. A dummy row or a dummy column is added to this type of problem, depending on the necessity, to make it a balanced problem. The problem can then be addressed in the same way as the balanced problem.

Methods of Solving Transportation Problems

There are three ways for determining the initial basic feasible solution. They are

1. NorthWest Corner Cell Method.

2. Vogel’s Approximation Method (VAM).

3. Least Call Cell Method.

The following is the basic framework of the balanced transportation problem:

Basic Structure of Balanced Transportation Problem

The destinations D1, D2, D3, and D4 in the above table are where the products/goods will be transported from various sources O1, O2, O3, and O4. The supply from the source Oi is represented by S i . The demand for the destination Dj is d j . If a product is delivered from source Si to destination Dj, then the cost is called C ij .

Let us now explore the process of solving the balanced transportation problem using one of the ways known as the NorthWest Corner Method in this article.

Solving Balanced Transportation problem by Northwest Corner Method

Consider this scenario:

Balanced Transportation Problem -1

With three sources (O1, O2, and O3) and four destinations (D1, D2, D3, and D4), what is the best way to solve this problem? The supply for the sources O1, O2, and O3 are 300, 400, and 500, respectively. Demands for the destination D1, D2, D3, and D4 are 250, 350, 400, and 200, respectively.

The starting point for the North West Corner technique is (O1, D1), which is the table’s northwest corner. The cost of transportation is calculated for each value in the cell. As indicated in the diagram, compare the demand for column D1 with the supply from source O1 and assign a minimum of two to the cell (O1, D1).

Column D1’s demand has been met, hence the entire column will be canceled. The supply from the source O1 is still 300 – 250 = 50.

Balanced Transportation Problem - 2

Analyze the northwest corner, i.e. (O1, D2), of the remaining table, excluding column D1, and assign the lowest among the supply for the appropriate column and rows. Because the supply from O1 is 50 and the demand for D2 is 350, allocate 50 to the cell (O1, D2).

Now, row O1 is canceled because the supply from row O1 has been completed. Hence, the demand for Column D2 has become 350 – 50 = 50.

Balanced Transportation Problem - 3

The northwest corner cell in the remaining table is (O2, D2). The shortest supply from source O2 (400) and the demand for column D2 (300) is 300, thus putting 300 in the cell (O2, D2). Because the demand for column D2 has been met, the column can be deleted, and the remaining supply from source O2 is 400 – 300 = 100.

Balanced Transportation Problem - 4

Again, find the northwest corner of the table, i.e. (O2, D3), and compare the O2 supply (i.e. 100) to the D2 demand (i.e. 400) and assign the smaller (i.e. 100) to the cell (O2, D2). Row O2 has been canceled because the supply from O2 has been completed. Column D3 has a leftover demand of 400 – 100 = 300.

Balanced Transportation Problem -5

Continuing in the same manner, the final cell values will be:

Balanced Transportation Problem - 6

It should be observed that the demand for the relevant columns and rows is equal in the last remaining cell, which was cell (O3, D4). In this situation, the supply from O3 was 200, and the demand for D4 was 200, therefore this cell was assigned to it. Nothing was left for any row or column at the end.

To achieve the basic solution, multiply the allotted value by the respective cell value (i.e. the cost) and add them all together.

I.e., (250 × 3) + (50 × 1) + (300 × 6) + (100 × 5) + (300 × 3) + (200 × 2) = 4400.

:

Solving Unbalanced Transportation Problem

An unbalanced transportation problem is provided below. Because the sum of all the supplies, O1, O2, O3, and O4, does not equal the sum of all the demands, D1, D2, D3, D4, and D5, the situation is unbalanced.

Unbalanced Transportation Problem - 1

The idea of a dummy row or dummy column will be applied in this type of scenario. Because the supply is more than the demand in this situation, a fake demand column will be inserted, with a demand of (total supply – total demand), i.e. 117 – 95 = 22, as seen in the image below. A fake supply row would have been introduced if demand was greater than supply.

Unbalanced Transportation Problem - 2

Now this problem has been changed to a balanced transportation problem, and it can be addressed using any of the ways listed below to solve a balanced transportation problem, such as the northwest corner method mentioned earlier.

Frequently Asked Questions on Balanced and Unbalanced Transportation Problems

What is meant by balanced and unbalanced transportation problems.

The problem is referred to as a balanced transportation problem when both supplies and demands are equal. Unbalanced transportation is defined as a situation where supply and demand are not equal.

What is called a transportation problem?

The transportation problem is a type of Linear Programming Problem in which commodities are carried from a set of sources to a set of destinations while taking into account the supply and demand of the sources and destinations, respectively, in order to reduce the total cost of transportation.

What are the different methods to solve transportation problems?

The following are three approaches to solve the transportation issue:

  • NorthWest Corner Cell Method.
  • Least Call Cell Method.
  • Vogel’s Approximation Method (VAM).
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Nash Balanced Assignment Problem

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  • First Online: 21 November 2022
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unbalanced assignment problem meaning

  • Minh Hieu Nguyen 11 ,
  • Mourad Baiou 11 &
  • Viet Hung Nguyen 11  

Part of the book series: Lecture Notes in Computer Science ((LNCS,volume 13526))

Included in the following conference series:

  • International Symposium on Combinatorial Optimization

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In this paper, we consider a variant of the classic Assignment Problem (AP), called the Balanced Assignment Problem (BAP) [ 2 ]. The BAP seeks to find an assignment solution which has the smallest value of max-min distance : the difference between the maximum assignment cost and the minimum one. However, by minimizing only the max-min distance, the total cost of the BAP solution is neglected and it may lead to an inefficient solution in terms of total cost. Hence, we propose a fair way based on Nash equilibrium [ 1 , 3 , 4 ] to inject the total cost into the objective function of the BAP for finding assignment solutions having a better trade-off between the two objectives: the first aims at minimizing the total cost and the second aims at minimizing the max-min distance. For this purpose, we introduce the concept of Nash Fairness (NF) solutions based on the definition of proportional-fair scheduling adapted in the context of the AP: a transfer of utilities between the total cost and the max-min distance is considered to be fair if the percentage increase in the total cost is smaller than the percentage decrease in the max-min distance and vice versa.

We first show the existence of a NF solution for the AP which is exactly the optimal solution minimizing the product of the total cost and the max-min distance. However, finding such a solution may be difficult as it requires to minimize a concave function. The main result of this paper is to show that finding all NF solutions can be done in polynomial time. For that, we propose a Newton-based iterative algorithm converging to NF solutions in polynomial time. It consists in optimizing a sequence of linear combinations of the two objective based on Weighted Sum Method [ 5 ]. Computational results on various instances of the AP are presented and commented.

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INP Clermont Auvergne, Univ Clermont Auvergne, Mines Saint-Etienne, CNRS, UMR 6158 LIMOS, 1 Rue de la Chebarde, Aubiere Cedex, France

Minh Hieu Nguyen, Mourad Baiou & Viet Hung Nguyen

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Correspondence to Viet Hung Nguyen .

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Editors and affiliations.

ESSEC Business School of Paris, Cergy Pontoise Cedex, France

Ivana Ljubić

IBM TJ Watson Research Center, Yorktown Heights, NY, USA

Francisco Barahona

Georgia Institute of Technology, Atlanta, GA, USA

Santanu S. Dey

Université Paris-Dauphine, Paris, France

A. Ridha Mahjoub

Proposition 1 . There may be more than one NF solution for the AP.

Let us illustrate this by an instance of the AP having the following cost matrix

By verifying all feasible assignment solutions in this instance, we obtain easily three assignment solutions \((1-1, 2-2, 3-3), (1-2, 2-3, 3-1)\) , \((1-3, 2-2, 3-1)\) and \((1-3, 2-1, 3-2)\) corresponding to 4 NF solutions (280, 36), (320, 32), (340, 30) and (364, 28). Note that \(i-j\) where \(1 \le i,j \le 3\) represents the assignment between worker i and job j in the solution of this instance.     \(\square \)

We recall below the proofs of some recent results that we have published in [ 10 ]. They are needed to prove the new results presented in this paper.

Theorem 2 [ 10 ] . \((P^{*},Q^{*}) = {{\,\mathrm{arg\,min}\,}}_{(P,Q) \in \mathcal {S}} PQ\) is a NF solution.

Obviously, there always exists a solution \((P^{*},Q^{*}) \in \mathcal {S}\) such that

Now \(\forall (P',Q') \in \mathcal {S}\) we have \(P'Q' \ge P^{*}Q^{*}\) . Then

The first inequality holds by the Cauchy-Schwarz inequality.

Hence, \((P^{*},Q^{*})\) is a NF solution.     \(\square \)

Theorem 3 [ 10 ] . \((P^{*},Q^{*}) \in \mathcal {S}\) is a NF solution if and only if \((P^{*},Q^{*})\) is an optimal solution of \(\mathcal {P(\alpha ^{*})}\) where \(\alpha ^{*} = \frac{Q^{*}}{P^{*}}\) .

Firstly, let \((P^{*},Q^{*})\) be a NF solution and \(\alpha ^{*} = \frac{Q^{*}}{P^{*}}\) . We will show that \((P^{*},Q^{*})\) is an optimal solution of \(\mathcal {P(\alpha ^{*})}\) .

Since \((P^{*},Q^{*})\) is a NF solution, we have

Since \(\alpha ^{*} = \frac{Q^{*}}{P^{*}}\) , we have \(\alpha ^{*}P^{*}+Q^{*} = 2Q^{*}\) .

Dividing two sides of ( 6 ) by \(P^{*} > 0\) we obtain

So we deduce from ( 7 )

Hence, \((P^{*},Q^{*})\) is an optimal solution of \(\mathcal {P}(\alpha ^{*})\) .

Now suppose \(\alpha ^{*} = \frac{Q^{*}}{P^{*}}\) and \((P^{*},Q^{*})\) is an optimal solution of \(\mathcal {P}(\alpha ^{*})\) , we show that \((P^{*},Q^{*})\) is a NF solution.

If \((P^{*},Q^{*})\) is not a NF solution, there exists a solution \((P',Q') \in \mathcal {S}\) such that

We have then

which contradicts the optimality of \((P^{*},Q^{*})\) .     \(\square \)

Lemma 3 [ 10 ] . Let \(\alpha , \alpha ' \in \mathbb {R}_+\) and \((P_{\alpha }, Q_{\alpha })\) , \((P_{\alpha '}, Q_{\alpha '})\) be the optimal solutions of \(\mathcal {P(\alpha )}\) and \(\mathcal {P(\alpha ')}\) respectively, if \(\alpha \le \alpha '\) then \(P_{\alpha } \ge P_{\alpha '}\) and \(Q_{\alpha } \le Q_{\alpha '}\) .

The optimality of \((P_{\alpha }, Q_{\alpha })\) and \((P_{\alpha '}, Q_{\alpha '})\) gives

By adding both sides of ( 8a ) and ( 8b ), we obtain \((\alpha - \alpha ') (P_{\alpha } - P_{\alpha '}) \le 0\) . Since \(\alpha \le \alpha '\) , it follows that \(P_{\alpha } \ge P_{\alpha '}\) .

On the other hand, inequality ( 8a ) implies \(Q_{\alpha '} - Q_{\alpha } \ge \alpha (P_{\alpha } - P_{\alpha '}) \ge 0\) that leads to \(Q_{\alpha } \le Q_{\alpha '}\) .     \(\square \)

Lemma 4 [ 10 ] . During the execution of Procedure Find ( \(\alpha _{0})\) in Algorithm 1 , \(\alpha _{i} \in [0,1], \, \forall i \ge 1\) . Moreover, if \(T_{0} \ge 0\) then the sequence \(\{\alpha _i\}\) is non-increasing and \(T_{i} \ge 0, \, \forall i \ge 0\) . Otherwise, if \(T_{0} \le 0\) then the sequence \(\{\alpha _i\}\) is non-decreasing and \(T_{i} \le 0, \, \forall i \ge 0\) .

Since \(P \ge Q \ge 0, \, \forall (P, Q) \in \mathcal {S}\) , it follows that \(\alpha _{i+1} = \frac{Q_i}{P_i} \in [0,1], \, \forall i \ge 0\) .

We first consider \(T_{0} \ge 0\) . We proof \(\alpha _i \ge \alpha _{i+1}, \, \forall i \ge 0\) by induction on i . For \(i = 0\) , we have \(T_{0} = \alpha _{0} P_{0} - Q_{0} = P_{0}(\alpha _{0}-\alpha _{1}) \ge 0\) , it follows that \(\alpha _{0} \ge \alpha _{1}\) . Suppose that our hypothesis is true until \(i = k \ge 0\) , we will prove that it is also true with \(i = k+1\) .

Indeed, we have

The inductive hypothesis gives \(\alpha _k \ge \alpha _{k+1}\) that implies \(P_{k+1} \ge P_k > 0\) and \(Q_{k} \ge Q_{k+1} \ge 0\) according to Lemma 3 . It leads to \(Q_{k}P_{k+1} - P_{k}Q_{k+1} \ge 0\) and then \(\alpha _{k+1} - \alpha _{k+2} \ge 0\) .

Hence, we have \(\alpha _{i} \ge \alpha _{i+1}, \, \forall i \ge 0\) .

Consequently, \(T_{i} = \alpha _{i}P_{i} - Q_{i} = P_{i}(\alpha _{i}-\alpha _{i+1}) \ge 0, \, \forall i \ge 0\) .

Similarly, if \(T_{0} \le 0\) we obtain that the sequence \(\{\alpha _i\}\) is non-decreasing and \(T_{i} \le 0, \, \forall i \ge 0\) . That concludes the proof.     \(\square \)

Lemma 5 [ 10 ] . From each \(\alpha _{0} \in [0,1]\) , Procedure Find \((\alpha _{0})\) converges to a coefficient \(\alpha _{k} \in \mathcal {C}_{0}\) satisfying \(\alpha _{k}\) is the unique element \(\in \mathcal {C}_{0}\) between \(\alpha _{0}\) and \(\alpha _{k}\) .

As a consequence of Lemma 4 , Procedure \(\textit{Find}(\alpha _{0})\) converges to a coefficient \(\alpha _{k} \in [0,1], \forall \alpha _{0} \in [0,1]\) .

By the stopping criteria of Procedure Find \((\alpha _{0})\) , when \(T_{k} = \alpha _{k} P_{k} - Q_{k} = 0\) we obtain \(\alpha _{k} \in C_{0}\) and \((P_{k},Q_{k})\) is a NF solution. (Theorem 3 )

If \(T_{0} = 0\) then obviously \(\alpha _{k} = \alpha _{0}\) . We consider \(T_{0} > 0\) and the sequence \(\{\alpha _i\}\) is now non-negative, non-increasing. We will show that \([\alpha _{k},\alpha _{0}] \cap \mathcal {C}_{0} = \alpha _{k}\) .

Suppose that we have \(\alpha \in (\alpha _{k},\alpha _{0}]\) and \(\alpha \in \mathcal {C}_{0}\) corresponding to a NF solution ( P ,  Q ). Then there exists \(1 \le i \le k\) such that \(\alpha \in (\alpha _{i}, \alpha _{i-1}]\) . Since \(\alpha \le \alpha _{i-1}\) , \(P \ge P_{i-1}\) and \(Q \le Q_{i-1}\) due to Lemma 3 . Thus, we get

By the definitions of \(\alpha \) and \(\alpha _{i}\) , inequality ( 9 ) is equivalent to \(\alpha \le \alpha _{i}\) which leads to a contradiction.

By repeating the same argument for \(T_{0} < 0\) , we also have a contradiction.     \(\square \)

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Nguyen, M.H., Baiou, M., Nguyen, V.H. (2022). Nash Balanced Assignment Problem. In: Ljubić, I., Barahona, F., Dey, S.S., Mahjoub, A.R. (eds) Combinatorial Optimization. ISCO 2022. Lecture Notes in Computer Science, vol 13526. Springer, Cham. https://doi.org/10.1007/978-3-031-18530-4_13

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MBA Notes

How to Solve the Assignment Problem: A Complete Guide

Table of Contents

Assignment problem is a special type of linear programming problem that deals with assigning a number of resources to an equal number of tasks in the most efficient way. The goal is to minimize the total cost of assignments while ensuring that each task is assigned to only one resource and each resource is assigned to only one task. In this blog, we will discuss the solution of the assignment problem using the Hungarian method, which is a popular algorithm for solving the problem.

Understanding the Assignment Problem

Before we dive into the solution, it is important to understand the problem itself. In the assignment problem, we have a matrix of costs, where each row represents a resource and each column represents a task. The objective is to assign each resource to a task in such a way that the total cost of assignments is minimized. However, there are certain constraints that need to be satisfied – each resource can be assigned to only one task and each task can be assigned to only one resource.

Solving the Assignment Problem

There are various methods for solving the assignment problem, including the Hungarian method, the brute force method, and the auction algorithm. Here, we will focus on the steps involved in solving the assignment problem using the Hungarian method, which is the most commonly used and efficient method.

Step 1: Set up the cost matrix

The first step in solving the assignment problem is to set up the cost matrix, which represents the cost of assigning a task to an agent. The matrix should be square and have the same number of rows and columns as the number of tasks and agents, respectively.

Step 2: Subtract the smallest element from each row and column

To simplify the calculations, we need to reduce the size of the cost matrix by subtracting the smallest element from each row and column. This step is called matrix reduction.

Step 3: Cover all zeros with the minimum number of lines

The next step is to cover all zeros in the matrix with the minimum number of horizontal and vertical lines. This step is called matrix covering.

Step 4: Test for optimality and adjust the matrix

To test for optimality, we need to calculate the minimum number of lines required to cover all zeros in the matrix. If the number of lines equals the number of rows or columns, the solution is optimal. If not, we need to adjust the matrix and repeat steps 3 and 4 until we get an optimal solution.

Step 5: Assign the tasks to the agents

The final step is to assign the tasks to the agents based on the optimal solution obtained in step 4. This will give us the most cost-effective or profit-maximizing assignment.

Solution of the Assignment Problem using the Hungarian Method

The Hungarian method is an algorithm that uses a step-by-step approach to find the optimal assignment. The algorithm consists of the following steps:

  • Subtract the smallest entry in each row from all the entries of the row.
  • Subtract the smallest entry in each column from all the entries of the column.
  • Draw the minimum number of lines to cover all zeros in the matrix. If the number of lines drawn is equal to the number of rows, we have an optimal solution. If not, go to step 4.
  • Determine the smallest entry not covered by any line. Subtract it from all uncovered entries and add it to all entries covered by two lines. Go to step 3.

The above steps are repeated until an optimal solution is obtained. The optimal solution will have all zeros covered by the minimum number of lines. The assignments can be made by selecting the rows and columns with a single zero in the final matrix.

Applications of the Assignment Problem

The assignment problem has various applications in different fields, including computer science, economics, logistics, and management. In this section, we will provide some examples of how the assignment problem is used in real-life situations.

Applications in Computer Science

The assignment problem can be used in computer science to allocate resources to different tasks, such as allocating memory to processes or assigning threads to processors.

Applications in Economics

The assignment problem can be used in economics to allocate resources to different agents, such as allocating workers to jobs or assigning projects to contractors.

Applications in Logistics

The assignment problem can be used in logistics to allocate resources to different activities, such as allocating vehicles to routes or assigning warehouses to customers.

Applications in Management

The assignment problem can be used in management to allocate resources to different projects, such as allocating employees to tasks or assigning budgets to departments.

Let’s consider the following scenario: a manager needs to assign three employees to three different tasks. Each employee has different skills, and each task requires specific skills. The manager wants to minimize the total time it takes to complete all the tasks. The skills and the time required for each task are given in the table below:

Task 1 Task 2 Task 3
Emp 1 5 7 6
Emp 2 6 4 5
Emp 3 8 5 3

The assignment problem is to determine which employee should be assigned to which task to minimize the total time required. To solve this problem, we can use the Hungarian method, which we discussed in the previous blog.

Using the Hungarian method, we first subtract the smallest entry in each row from all the entries of the row:

Task 1 Task 2 Task 3
Emp 1 0 2 1
Emp 2 2 0 1
Emp 3 5 2 0

Next, we subtract the smallest entry in each column from all the entries of the column:

Task 1 Task 2 Task 3
Emp 1 0 2 1
Emp 2 2 0 1
Emp 3 5 2 0
0 0 0

We draw the minimum number of lines to cover all the zeros in the matrix, which in this case is three:

Since the number of lines is equal to the number of rows, we have an optimal solution. The assignments can be made by selecting the rows and columns with a single zero in the final matrix. In this case, the optimal assignments are:

  • Emp 1 to Task 3
  • Emp 2 to Task 2
  • Emp 3 to Task 1

This assignment results in a total time of 9 units.

I hope this example helps you better understand the assignment problem and how to solve it using the Hungarian method.

Solving the assignment problem may seem daunting, but with the right approach, it can be a straightforward process. By following the steps outlined in this guide, you can confidently tackle any assignment problem that comes your way.

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Operations Research

1 Operations Research-An Overview

  • History of O.R.
  • Approach, Techniques and Tools
  • Phases and Processes of O.R. Study
  • Typical Applications of O.R
  • Limitations of Operations Research
  • Models in Operations Research
  • O.R. in real world

2 Linear Programming: Formulation and Graphical Method

  • General formulation of Linear Programming Problem
  • Optimisation Models
  • Basics of Graphic Method
  • Important steps to draw graph
  • Multiple, Unbounded Solution and Infeasible Problems
  • Solving Linear Programming Graphically Using Computer
  • Application of Linear Programming in Business and Industry

3 Linear Programming-Simplex Method

  • Principle of Simplex Method
  • Computational aspect of Simplex Method
  • Simplex Method with several Decision Variables
  • Two Phase and M-method
  • Multiple Solution, Unbounded Solution and Infeasible Problem
  • Sensitivity Analysis
  • Dual Linear Programming Problem

4 Transportation Problem

  • Basic Feasible Solution of a Transportation Problem
  • Modified Distribution Method
  • Stepping Stone Method
  • Unbalanced Transportation Problem
  • Degenerate Transportation Problem
  • Transhipment Problem
  • Maximisation in a Transportation Problem

5 Assignment Problem

  • Solution of the Assignment Problem
  • Unbalanced Assignment Problem
  • Problem with some Infeasible Assignments
  • Maximisation in an Assignment Problem
  • Crew Assignment Problem

6 Application of Excel Solver to Solve LPP

  • Building Excel model for solving LP: An Illustrative Example

7 Goal Programming

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  • The simplex method of goal programming
  • Using Excel Solver to Solve Goal Programming Models
  • Application areas of goal programming

8 Integer Programming

  • Some Integer Programming Formulation Techniques
  • Binary Representation of General Integer Variables
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Balancing an Unbalanced Assignment problem using optimization techniques

How can I balance the following assignment problem (where machines are to be assigned the jobs in optimal way such that the profit is maximized). Cost matrix is given in the problem.

Cost matrix is given in problem

First step is to convert it into minimization problem by subtracting all the entries in the matrix from maximum value in the matrix.

In next step, We try to balance the unbalanced problem i.e. adding dummy machines in this case. How to do this step? What should be row entries for dummy machines in matrix.

  • convex-optimization
  • linear-programming
  • discrete-optimization

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unbalanced assignment problem meaning

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What is Balanced or Unbalanced Assignment problem?

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The Assignment problem can be Balanced or Unbalanced problem.

A Balanced problem means the no. of rows and no. of columns in the problem are equal. E. g. if the problem contains 4 workers and 4 jobs, then it is balanced.

Where as, an Unbalanced problem means the no. of rows and no. of columns are not equal. E. g. if the problem contains 4 workers and 3 jobs it is not balanced. Then first we need to balance the problem by taking a Dummy job (imaginary job).

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IMAGES

  1. MEANING OF UNBALANCED ASSIGNMENT PROBLEM WITH EXAMPLE BY DR KUNAL

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  2. Unbalanced Assignment Problem

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  3. Unbalanced Assignment Problems, Easy Explanation and Easy Method with

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  4. UNBALANCED ASSIGNMENT PROBLEM EXAMPLE NO. 1 BY DR KUNAL KHATRI #STATISTICS4ALL #ASSIGNMENT #EDU

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  5. Assignment Problem example 3 (unbalanced problem)

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  6. EASY STEPS TO SOLVE UNBALANCED AND CONSTRAINED ASSIGNMENT PROBLEM PART 1

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VIDEO

  1. Assignment Problem (Unbalanced)

  2. Assignment problem part ii

  3. MAXIMIZATION & UNBALANCED PROBLEM ||ASSIGNMENT PROBLEM|| OPERATIONS RESEARCH|| Lecture

  4. unbalanced assignment problem

  5. Unbalanced Assignment Problem

  6. Assignment problem (unbalanced) (dummy)

COMMENTS

  1. Unbalanced Assignment Problem: Definition, Formulation, and Solution

    The Unbalanced Assignment Problem is an extension of the Assignment Problem in OR, where the number of tasks and workers is not equal. In the UAP, some tasks may remain unassigned, while some workers may not be assigned any task. The objective is still to minimize the total cost or time required to complete the assigned tasks, but the UAP has ...

  2. Unbalanced Assignment Problems

    10 Feb 2019. Whenever the cost matrix of an assignment problem is not a square matrix, that is, whenever the number of sources is not equal to the number of destinations, the assignment problem is called an unbalanced assignment problem. In such problems, dummy rows (or columns) are added in the matrix so as to complete it to form a square matrix.

  3. Assignment problem

    The assignment problem consists of finding, in a weighted bipartite graph, a matching of a given size, in which the sum of weights of the edges is minimum. If the numbers of agents and tasks are equal, then the problem is called balanced assignment. Otherwise, it is called unbalanced assignment. [1] If the total cost of the assignment for all ...

  4. Linear assignment with non-perfect matching

    Most libraries for the assignment problem solve either the balanced or unbalanced version of this problem (see the later section). However, whether balanced or unbalanced, it may still occur that the constraint set is infeasible, meaning that there does not exist a (one-sided) perfect matching.

  5. Unbalanced Assignment Problem

    Unbalanced Assignment problem is an assignment problem where the number of facilities is not equal to the number of jobs. To make unbalanced assignment problem, a balanced one, a dummy facility (s) or a dummy job (s) (as the case may be) is introduced with zero cost or time. Get Quantitative Techniques: Theory and Problems now with the O ...

  6. Unbalanced Assignment Problem

    Example: Unbalanced Assignment Problem. Solution. Since the number of persons is less than the number of jobs, we introduce a dummy person (D) with zero values. The revised assignment problem is given below: Table. Now use the Hungarian method to obtain the optimal solution yourself. Ans. = 20 + 17 + 17 + 0 = 54.

  7. PDF UNIT -2 Chapter: II ASSIGNMENT PROBLEM

    Unbalanced Assignment Problem: Unbalanced Assignment problem is an assignment problem where the number of facilities is not equal to the number of jobs. To make unbalanced assignment problem, a balanced one, a dummy facility(s) or a dummy job(s) (as the case may be) is introduced with zero cost or time. Dummy Job/Facility: ...

  8. A Comparative Analysis of Assignment Problem

    unbalanced assignment problems is based on the assumption that some jobs should be assigned to pseudo or dummy machines, but these jobs are left unexecuted by the dummy machines in the Hungarian method. However, it is sometimes impractical in real-world situations. Moreover, Lampang, Boonjing, and Chanvarasuth introduced a new space- ...

  9. PDF Solving the Unbalanced Assignment Problem: Simpler Is Better

    The typical textbook solution to the balanced assignment problem is then found using Kuhn's [3] Hungarian method. Problems in which there are more jobs than machines and more than one job can be ...

  10. Solving the Unbalanced Assignment Problem: Simpler Is Better

    For unbalanced assignment problem where the number of jobs is more than the number of machines, the existing approaches assign some jobs to a dummy machine which means these jobs are left without ...

  11. Assignment Problem: Meaning, Methods and Variations

    After reading this article you will learn about:- 1. Meaning of Assignment Problem 2. Definition of Assignment Problem 3. Mathematical Formulation 4. Hungarian Method 5. Variations. Meaning of Assignment Problem: An assignment problem is a particular case of transportation problem where the objective is to assign a number of resources to an equal number of activities so as to minimise total ...

  12. Assignment Problem

    Unbalanced Assignment Problem. If the cost matrix of an assignment problem is not a square matrix, the assignment problem is called an Unbalanced Assignment Problem. In such a case, add dummy row or dummy column with zero cost in the cost matrix so as to form a square matrix. Then apply the usual assignment method to find the optimal solution.

  13. Solving the Unbalanced Assignment Problem: Simpler Is Better

    7. PDF. Recently, Yadaiah and Haragopal published in the American Journal of Operations Research a new approach to solving the unbalanced assignment problem. They also provide a numerical example which they solve with their approach and get a cost of 1550 which they claim is optimum. This approach might be of interest; however, their approach ...

  14. Solving the Unbalanced Assignment Problem: Simpler Is Better

    The assignment problems are a well studied topic in combinatorial optimization. These problems find numerous application in production planning, telecommunication VLSI design, economic etc. The assignment problems is a special case of Transportation problem. Depending on the objective we want to optimize, we obtain the typical assignment problems.

  15. 4. Unbalanced Assignment Problem

    4. Unbalanced Assignment Problem. Unbalanced Assignment Problem If number of rows is not equal to number of columns then it is called Unbalanced Assignment Problem. So to solve this problem, we have to add dummy rows or columns with cost 0, to make it a square matrix. ExampleFind Solution of Assignment problem using Hungarian method (MIN case)

  16. An Alternative Approach for Solving Unbalanced Assignment Problems

    Unbalanced assignment problem, Hungarian method, Optimal solution. Introduction The assignment problem is a combinatorial optimization problem in the field of operations research. It is a special case and completely degenerate form of a transportation problem, which occurs when each supply is 1 and

  17. Novel optimization method for unbalanced assignment problems with

    Problem definition: unbalanced assignment problem with multiple jobs. The Unbalanced Assignment Problem deals with processing n tasks to m agents (n and m are integers and different) where each task is exactly affected to only one agent and each agent needs to carry out at least one task (and no more than q tasks). The main objective is to ...

  18. Balanced and Unbalanced Transportation Problems

    Unbalanced transportation problem is defined as a situation in which supply and demand are not equal. A dummy row or a dummy column is added to this type of problem, depending on the necessity, to make it a balanced problem. The problem can then be addressed in the same way as the balanced problem.

  19. Nash Balanced Assignment Problem

    The Assignment Problem (AP) is a fundamental combinatorial optimization problem. It can be formally defined as follows. Given a set n workers, a set of n jobs and a \(n \times n\) cost matrix whose elements are positive representing the assignment of any worker to any job, the AP aims at finding an one-to-one worker-job assignment (i.e., a bipartite perfect matching) that minimizes certain ...

  20. How to Solve the Assignment Problem: A Complete Guide

    Step 1: Set up the cost matrix. The first step in solving the assignment problem is to set up the cost matrix, which represents the cost of assigning a task to an agent. The matrix should be square and have the same number of rows and columns as the number of tasks and agents, respectively.

  21. linear programming

    How can I balance the following assignment problem (where machines are to be assigned the jobs in optimal way such that the profit is maximized). Cost matrix is given in the problem. First step is to convert it into minimization problem by subtracting all the entries in the matrix from maximum value in the matrix.

  22. Assignment problems

    Unit 8: Assignment Problem - Unbalanced. When an assignment problem has more than one solution, then it is Notes (a) Multiple Optimal solution (b) The problem is unbalanced (c) Maximization problem (d) Balanced problem. 8 Unbalanced Assignment Problem. If the given matrix is not a square matrix, the assignment problem is called an unbalanced ...

  23. What is Balanced or Unbalanced Assignment problem?

    The Assignment problem can be Balanced or Unbalanced problem.. A Balanced problem means the no. of rows and no. of columns in the problem are equal. E. g. if the problem contains 4 workers and 4 jobs, then it is balanced. Where as, an Unbalanced problem means the no. of rows and no. of columns are not equal.E. g. if the problem contains 4 workers and 3 jobs it is not balanced.