8. Restrictions and Unbalanced Assignment Problem
Find Solution of Assignment problem using Hungarian method (MIN case)
Work\Job | A | B | C | D | E | M1 | 9 | 11 | 15 | 10 | 11 | M2 | 12 | 9 | - | 10 | 9 | M3 | - | 11 | 14 | 11 | 7 | M4 | 14 | 8 | 12 | 7 | 8 |
Solution: The number of rows = 4 and columns = 5
| `A` | `B` | `C` | `D` | `E` | | `M_1` | 9 | 11 | 15 | 10 | 11 | | `M_2` | 12 | 9 | M | 10 | 9 | | `M_3` | M | 11 | 14 | 11 | 7 | | `M_4` | 14 | 8 | 12 | 7 | 8 | | | | | | | | |
Here given problem is unbalanced and add 1 new row to convert it into a balance.
| `A` | `B` | `C` | `D` | `E` | | `M_1` | 9 | 11 | 15 | 10 | 11 | | `M_2` | 12 | 9 | M | 10 | 9 | | `M_3` | M | 11 | 14 | 11 | 7 | | `M_4` | 14 | 8 | 12 | 7 | 8 | | `W_5` | 0 | 0 | 0 | 0 | 0 | | | | | | | | |
Step-1: Find out the each row minimum element and subtract it from that row
| `A` | `B` | `C` | `D` | `E` | | `M_1` | 0 `0=9-9` | 2 `2=11-9` | 6 `6=15-9` | 1 `1=10-9` | 2 `2=11-9` | (-9) Minimum element of `1^(st)` row | `M_2` | 3 `3=12-9` | 0 `0=9-9` | M M | 1 `1=10-9` | 0 `0=9-9` | (-9) Minimum element of `2^(nd)` row | `M_3` | M M | 4 `4=11-7` | 7 `7=14-7` | 4 `4=11-7` | 0 `0=7-7` | (-7) Minimum element of `3^(rd)` row | `M_4` | 7 `7=14-7` | 1 `1=8-7` | 5 `5=12-7` | 0 `0=7-7` | 1 `1=8-7` | (-7) Minimum element of `4^(th)` row | `W_5` | 0 `0=0-0` | 0 `0=0-0` | 0 `0=0-0` | 0 `0=0-0` | 0 `0=0-0` | (-0) Minimum element of `5^(th)` row | | | | | | | |
Step-2: Find out the each column minimum element and subtract it from that column.
| `A` | `B` | `C` | `D` | `E` | | `M_1` | 0 `0=0-0` | 2 `2=2-0` | 6 `6=6-0` | 1 `1=1-0` | 2 `2=2-0` | | `M_2` | 3 `3=3-0` | 0 `0=0-0` | M M | 1 `1=1-0` | 0 `0=0-0` | | `M_3` | M M | 4 `4=4-0` | 7 `7=7-0` | 4 `4=4-0` | 0 `0=0-0` | | `M_4` | 7 `7=7-0` | 1 `1=1-0` | 5 `5=5-0` | 0 `0=0-0` | 1 `1=1-0` | | `W_5` | 0 `0=0-0` | 0 `0=0-0` | 0 `0=0-0` | 0 `0=0-0` | 0 `0=0-0` | | | (-0) Minimum element of `1^(st)` column | (-0) Minimum element of `2^(nd)` column | (-0) Minimum element of `3^(rd)` column | (-0) Minimum element of `4^(th)` column | (-0) Minimum element of `5^(th)` column | |
Step-3: Make assignment in the opporunity cost tablea. Identify rows with exactly one unmarked 0. Make an assignmment to this single 0 by make a square ( [0] ) around it and cross off all other 0 in the same column. b. Identify columns with exactly one unmarked 0. Make an assignmment to this single 0 by make a square ( [0] ) around it and cross off all other 0 in the same rows. c. If a row and/or column has two or more unmarked 0 and one cannot be chosen by inspection, then choose the cell arbitarily. d. Continue this process until all 0 in rows/columns are either assigned or cross off( ). Step-3: Make assignment in the opporunity cost table (1) Rowwise cell `(M_1,A)` is assigned, so columnwise cell `(W_5,A)` crossed off.
(2) Rowwise cell `(M_3,E)` is assigned, so columnwise cell `(M_2,E)`,`(W_5,E)` crossed off.
(3) Rowwise cell `(M_4,D)` is assigned, so columnwise cell `(W_5,D)` crossed off.
(4) Columnwise cell `(W_5,C)` is assigned, so rowwise cell `(W_5,B)` crossed off.
(5) Rowwise cell `(M_2,B)` is assigned
Rowwise & columnwise assignment shown in table
| `A` | `B` | `C` | `D` | `E` | | `M_1` | [0] (1) Rowwise cell `(M_1,A)` is assigned so columnwise cell `(W_5,A)` crossed off. | 2 | 6 | 1 | 2 | | `M_2` | 3 | [0] (5) Rowwise cell `(M_2,B)` is assigned | M | 1 | 0 Columnwise `(M_2,E)` crossed off because (2) Rowwise cell `(M_3,E)` is assigned | | `M_3` | M | 4 | 7 | 4 | [0] (2) Rowwise cell `(M_3,E)` is assigned so columnwise cell `(M_2,E)`,`(W_5,E)` crossed off. | | `M_4` | 7 | 1 | 5 | [0] (3) Rowwise cell `(M_4,D)` is assigned so columnwise cell `(W_5,D)` crossed off. | 1 | | `W_5` | 0 Columnwise `(W_5,A)` crossed off because (1) Rowwise cell `(M_1,A)` is assigned | 0 Rowwise `(W_5,B)` crossed off because (4) Columnwise cell `(W_5,C)` is assigned | [0] (4) Columnwise cell `(W_5,C)` is assigned so rowwise cell `(W_5,B)` crossed off. | 0 Columnwise `(W_5,D)` crossed off because (3) Rowwise cell `(M_4,D)` is assigned | 0 Columnwise `(W_5,E)` crossed off because (2) Rowwise cell `(M_3,E)` is assigned | | | | | | | | |
Step-4: Number of assignments = 5, number of rows = 5 Which is equal, so solution is optimal
Optimal assignments are
| `A` | `B` | `C` | `D` | `E` | | `M_1` | [0] Original cost 9 | 2 Original cost 11 | 6 Original cost 15 | 1 Original cost 10 | 2 Original cost 11 | | `M_2` | 3 Original cost 12 | [0] Original cost 9 | M Original cost M | 1 Original cost 10 | 0 Original cost 9 | | `M_3` | M Original cost M | 4 Original cost 11 | 7 Original cost 14 | 4 Original cost 11 | [0] Original cost 7 | | `M_4` | 7 Original cost 14 | 1 Original cost 8 | 5 Original cost 12 | [0] Original cost 7 | 1 Original cost 8 | | `W_5` | 0 Original cost 0 | 0 Original cost 0 | [0] Original cost 0 | 0 Original cost 0 | 0 Original cost 0 | | | | | | | | |
Optimal solution is
Work | Job | Cost | `M_1` | `A` | 9 | `M_2` | `B` | 9 | `M_3` | `E` | 7 | `M_4` | `D` | 7 | `W_5` | `C` | 0 | | Total | 32 |
This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
|