1. Algorithm & Example-1
Algorithm
Russell's Approximation Method (RAM):
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Step-1:
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For each source row still under consideration, determine its `bar U_i` (largest cost in row i).
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Step-2:
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For each destination column still under consideration, determine its `bar V_j` (largest cost in column j).
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Step-3:
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For each variable, calculate `Delta_(ij) = c_(ij) - (bar U_i + bar V_j)`.
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Step-4:
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Select the variable having the most negative `Delta` value, break ties arbitrarily.
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Step-5:
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Allocate as much as possible. Eliminate necessary cells from consideration. Return to Step-1.
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Example-1
1. Find Solution using Russell's Approximation method
| D1 | D2 | D3 | D4 | Supply | S1 | 19 | 30 | 50 | 10 | 7 | S2 | 70 | 30 | 40 | 60 | 9 | S3 | 40 | 8 | 70 | 20 | 18 | Demand | 5 | 8 | 7 | 14 | |
Solution: TOTAL number of supply constraints : 3 TOTAL number of demand constraints : 4 Problem Table is
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `S_1` | 19 | 30 | 50 | 10 | | 7 | `S_2` | 70 | 30 | 40 | 60 | | 9 | `S_3` | 40 | 8 | 70 | 20 | | 18 | | Demand | 5 | 8 | 7 | 14 | | |
Table-1: Calculate `bar U_i` and `bar V_j` (where `bar U_i` is the largest cost in row and `bar V_j` is the largest cost in column)
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19 | 30 | 50 | 10 | | 7 | `50` | `S_2` | 70 | 30 | 40 | 60 | | 9 | `70` | `S_3` | 40 | 8 | 70 | 20 | | 18 | `70` | | Demand | 5 | 8 | 7 | 14 | | | | `bar V_j` | `70` | `30` | `70` | `60` | | | |
2. Compute reduced cost of each cell `Delta_(ij)`, where `Delta_(ij) = c_(ij) - (bar U_i + bar V_j)`
`1. Delta_11 = c_11 - (bar U_1 + bar V_1) = 19 - (50 +70) = color{blue}{-101} `
`2. Delta_12 = c_12 - (bar U_1 + bar V_2) = 30 - (50 +30) = color{blue}{-50} `
`3. Delta_13 = c_13 - (bar U_1 + bar V_3) = 50 - (50 +70) = color{blue}{-70} `
`4. Delta_14 = c_14 - (bar U_1 + bar V_4) = 10 - (50 +60) = color{blue}{-100} `
`5. Delta_21 = c_21 - (bar U_2 + bar V_1) = 70 - (70 +70) = color{blue}{-70} `
`6. Delta_22 = c_22 - (bar U_2 + bar V_2) = 30 - (70 +30) = color{blue}{-70} `
`7. Delta_23 = c_23 - (bar U_2 + bar V_3) = 40 - (70 +70) = color{blue}{-100} `
`8. Delta_24 = c_24 - (bar U_2 + bar V_4) = 60 - (70 +60) = color{blue}{-70} `
`9. Delta_31 = c_31 - (bar U_3 + bar V_1) = 40 - (70 +70) = color{blue}{-100} `
`10. Delta_32 = c_32 - (bar U_3 + bar V_2) = 8 - (70 +30) = color{blue}{-92} `
`11. Delta_33 = c_33 - (bar U_3 + bar V_3) = 70 - (70 +70) = color{blue}{-70} `
`12. Delta_34 = c_34 - (bar U_3 + bar V_4) = 20 - (70 +60) = color{blue}{-110} `
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19 [-101] | 30 [-50] | 50 [-70] | 10 [-100] | | 7 | `50` | `S_2` | 70 [-70] | 30 [-70] | 40 [-100] | 60 [-70] | | 9 | `70` | `S_3` | 40 [-100] | 8 [-92] | 70 [-70] | 20 [-110] | | 18 | `70` | | Demand | 5 | 8 | 7 | 14 | | | | `bar V_j` | `70` | `30` | `70` | `60` | | | |
The most negative `Delta_(ij)` is -110 in cell `S_3 D_4`
The allocation to this cell is min(18,14) = 14. This satisfies the entire demand of `D_4` and leaves 18 - 14 = 4 units with `S_3`
Table-1: This leads to the following table
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `S_1` | 19 | 30 | 50 | 10 | | 7 | `S_2` | 70 | 30 | 40 | 60 | | 9 | `S_3` | 40 | 8 | 70 | 20 (14) | | 4 | | Demand | 5 | 8 | 7 | 0 | | |
Table-2: Calculate `bar U_i` and `bar V_j` (where `bar U_i` is the largest cost in row and `bar V_j` is the largest cost in column)
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19 | 30 | 50 | 10 | | 7 | `50` | `S_2` | 70 | 30 | 40 | 60 | | 9 | `70` | `S_3` | 40 | 8 | 70 | 20(14) | | 4 | `70` | | Demand | 5 | 8 | 7 | 0 | | | | `bar V_j` | `70` | `30` | `70` | -- | | | |
2. Compute reduced cost of each cell `Delta_(ij)`, where `Delta_(ij) = c_(ij) - (bar U_i + bar V_j)`
`1. Delta_11 = c_11 - (bar U_1 + bar V_1) = 19 - (50 +70) = color{blue}{-101} `
`2. Delta_12 = c_12 - (bar U_1 + bar V_2) = 30 - (50 +30) = color{blue}{-50} `
`3. Delta_13 = c_13 - (bar U_1 + bar V_3) = 50 - (50 +70) = color{blue}{-70} `
`4. Delta_21 = c_21 - (bar U_2 + bar V_1) = 70 - (70 +70) = color{blue}{-70} `
`5. Delta_22 = c_22 - (bar U_2 + bar V_2) = 30 - (70 +30) = color{blue}{-70} `
`6. Delta_23 = c_23 - (bar U_2 + bar V_3) = 40 - (70 +70) = color{blue}{-100} `
`7. Delta_31 = c_31 - (bar U_3 + bar V_1) = 40 - (70 +70) = color{blue}{-100} `
`8. Delta_32 = c_32 - (bar U_3 + bar V_2) = 8 - (70 +30) = color{blue}{-92} `
`9. Delta_33 = c_33 - (bar U_3 + bar V_3) = 70 - (70 +70) = color{blue}{-70} `
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19 [-101] | 30 [-50] | 50 [-70] | 10 | | 7 | `50` | `S_2` | 70 [-70] | 30 [-70] | 40 [-100] | 60 | | 9 | `70` | `S_3` | 40 [-100] | 8 [-92] | 70 [-70] | 20(14) | | 4 | `70` | | Demand | 5 | 8 | 7 | 0 | | | | `bar V_j` | `70` | `30` | `70` | -- | | | |
The most negative `Delta_(ij)` is -101 in cell `S_1 D_1`
The allocation to this cell is min(7,5) = 5. This satisfies the entire demand of `D_1` and leaves 7 - 5 = 2 units with `S_1`
Table-2: This leads to the following table
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `S_1` | 19 (5) | 30 | 50 | 10 | | 2 | `S_2` | 70 | 30 | 40 | 60 | | 9 | `S_3` | 40 | 8 | 70 | 20 (14) | | 4 | | Demand | 0 | 8 | 7 | 0 | | |
Table-3: Calculate `bar U_i` and `bar V_j` (where `bar U_i` is the largest cost in row and `bar V_j` is the largest cost in column)
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19(5) | 30 | 50 | 10 | | 2 | `50` | `S_2` | 70 | 30 | 40 | 60 | | 9 | `40` | `S_3` | 40 | 8 | 70 | 20(14) | | 4 | `70` | | Demand | 0 | 8 | 7 | 0 | | | | `bar V_j` | -- | `30` | `70` | -- | | | |
2. Compute reduced cost of each cell `Delta_(ij)`, where `Delta_(ij) = c_(ij) - (bar U_i + bar V_j)`
`1. Delta_12 = c_12 - (bar U_1 + bar V_2) = 30 - (50 +30) = color{blue}{-50} `
`2. Delta_13 = c_13 - (bar U_1 + bar V_3) = 50 - (50 +70) = color{blue}{-70} `
`3. Delta_22 = c_22 - (bar U_2 + bar V_2) = 30 - (40 +30) = color{blue}{-40} `
`4. Delta_23 = c_23 - (bar U_2 + bar V_3) = 40 - (40 +70) = color{blue}{-70} `
`5. Delta_32 = c_32 - (bar U_3 + bar V_2) = 8 - (70 +30) = color{blue}{-92} `
`6. Delta_33 = c_33 - (bar U_3 + bar V_3) = 70 - (70 +70) = color{blue}{-70} `
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19(5) | 30 [-50] | 50 [-70] | 10 | | 2 | `50` | `S_2` | 70 | 30 [-40] | 40 [-70] | 60 | | 9 | `40` | `S_3` | 40 | 8 [-92] | 70 [-70] | 20(14) | | 4 | `70` | | Demand | 0 | 8 | 7 | 0 | | | | `bar V_j` | -- | `30` | `70` | -- | | | |
The most negative `Delta_(ij)` is -92 in cell `S_3 D_2`
The allocation to this cell is min(4,8) = 4. This exhausts the capacity of `S_3` and leaves 8 - 4 = 4 units with `D_2`
Table-3: This leads to the following table
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `S_1` | 19 (5) | 30 | 50 | 10 | | 2 | `S_2` | 70 | 30 | 40 | 60 | | 9 | `S_3` | 40 | 8 (4) | 70 | 20 (14) | | 0 | | Demand | 0 | 4 | 7 | 0 | | |
Table-4: Calculate `bar U_i` and `bar V_j` (where `bar U_i` is the largest cost in row and `bar V_j` is the largest cost in column)
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19(5) | 30 | 50 | 10 | | 2 | `50` | `S_2` | 70 | 30 | 40 | 60 | | 9 | `40` | `S_3` | 40 | 8(4) | 70 | 20(14) | | 0 | -- | | Demand | 0 | 4 | 7 | 0 | | | | `bar V_j` | -- | `30` | `50` | -- | | | |
2. Compute reduced cost of each cell `Delta_(ij)`, where `Delta_(ij) = c_(ij) - (bar U_i + bar V_j)`
`1. Delta_12 = c_12 - (bar U_1 + bar V_2) = 30 - (50 +30) = color{blue}{-50} `
`2. Delta_13 = c_13 - (bar U_1 + bar V_3) = 50 - (50 +50) = color{blue}{-50} `
`3. Delta_22 = c_22 - (bar U_2 + bar V_2) = 30 - (40 +30) = color{blue}{-40} `
`4. Delta_23 = c_23 - (bar U_2 + bar V_3) = 40 - (40 +50) = color{blue}{-50} `
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19(5) | 30 [-50] | 50 [-50] | 10 | | 2 | `50` | `S_2` | 70 | 30 [-40] | 40 [-50] | 60 | | 9 | `40` | `S_3` | 40 | 8(4) | 70 | 20(14) | | 0 | -- | | Demand | 0 | 4 | 7 | 0 | | | | `bar V_j` | -- | `30` | `50` | -- | | | |
The most negative `Delta_(ij)` is -50 in cell `S_2 D_3`
The allocation to this cell is min(9,7) = 7. This satisfies the entire demand of `D_3` and leaves 9 - 7 = 2 units with `S_2`
Table-4: This leads to the following table
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `S_1` | 19 (5) | 30 | 50 | 10 | | 2 | `S_2` | 70 | 30 | 40 (7) | 60 | | 2 | `S_3` | 40 | 8 (4) | 70 | 20 (14) | | 0 | | Demand | 0 | 4 | 0 | 0 | | |
Table-5: Calculate `bar U_i` and `bar V_j` (where `bar U_i` is the largest cost in row and `bar V_j` is the largest cost in column)
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19(5) | 30 | 50 | 10 | | 2 | `30` | `S_2` | 70 | 30 | 40(7) | 60 | | 2 | `30` | `S_3` | 40 | 8(4) | 70 | 20(14) | | 0 | -- | | Demand | 0 | 4 | 0 | 0 | | | | `bar V_j` | -- | `30` | -- | -- | | | |
2. Compute reduced cost of each cell `Delta_(ij)`, where `Delta_(ij) = c_(ij) - (bar U_i + bar V_j)`
`1. Delta_12 = c_12 - (bar U_1 + bar V_2) = 30 - (30 +30) = color{blue}{-30} `
`2. Delta_22 = c_22 - (bar U_2 + bar V_2) = 30 - (30 +30) = color{blue}{-30} `
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19(5) | 30 [-30] | 50 | 10 | | 2 | `30` | `S_2` | 70 | 30 [-30] | 40(7) | 60 | | 2 | `30` | `S_3` | 40 | 8(4) | 70 | 20(14) | | 0 | -- | | Demand | 0 | 4 | 0 | 0 | | | | `bar V_j` | -- | `30` | -- | -- | | | |
The most negative `Delta_(ij)` is -30 in cell `S_1 D_2`
The allocation to this cell is min(2,4) = 2. This exhausts the capacity of `S_1` and leaves 4 - 2 = 2 units with `D_2`
Table-5: This leads to the following table
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `S_1` | 19 (5) | 30 (2) | 50 | 10 | | 0 | `S_2` | 70 | 30 | 40 (7) | 60 | | 2 | `S_3` | 40 | 8 (4) | 70 | 20 (14) | | 0 | | Demand | 0 | 2 | 0 | 0 | | |
Table-6: Calculate `bar U_i` and `bar V_j` (where `bar U_i` is the largest cost in row and `bar V_j` is the largest cost in column)
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19(5) | 30(2) | 50 | 10 | | 0 | -- | `S_2` | 70 | 30 | 40(7) | 60 | | 2 | `30` | `S_3` | 40 | 8(4) | 70 | 20(14) | | 0 | -- | | Demand | 0 | 2 | 0 | 0 | | | | `bar V_j` | -- | `30` | -- | -- | | | |
2. Compute reduced cost of each cell `Delta_(ij)`, where `Delta_(ij) = c_(ij) - (bar U_i + bar V_j)`
`1. Delta_22 = c_22 - (bar U_2 + bar V_2) = 30 - (30 +30) = color{blue}{-30} `
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `bar U_i` | `S_1` | 19(5) | 30(2) | 50 | 10 | | 0 | -- | `S_2` | 70 | 30 [-30] | 40(7) | 60 | | 2 | `30` | `S_3` | 40 | 8(4) | 70 | 20(14) | | 0 | -- | | Demand | 0 | 2 | 0 | 0 | | | | `bar V_j` | -- | `30` | -- | -- | | | |
The most negative `Delta_(ij)` is -30 in cell `S_2 D_2`
The allocation to this cell is min(2,2) = 2. Table-6: This leads to the following table
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `S_1` | 19 (5) | 30 (2) | 50 | 10 | | 0 | `S_2` | 70 | 30 (2) | 40 (7) | 60 | | 0 | `S_3` | 40 | 8 (4) | 70 | 20 (14) | | 0 | | Demand | 0 | 0 | 0 | 0 | | |
Initial feasible solution is
| `D_1` | `D_2` | `D_3` | `D_4` | | Supply | `S_1` | 19 (5) | 30 (2) | 50 | 10 | | 7 | `S_2` | 70 | 30 (2) | 40 (7) | 60 | | 9 | `S_3` | 40 | 8 (4) | 70 | 20 (14) | | 18 | | Demand | 5 | 8 | 7 | 14 | | |
The minimum total transportation cost `= 19 xx 5 + 30 xx 2 + 30 xx 2 + 40 xx 7 + 8 xx 4 + 20 xx 14 = 807`
Here, the number of allocated cells = 6 is equal to m + n - 1 = 3 + 4 - 1 = 6 `:.` This solution is non-degenerate
This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
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