1. Find Solution of game theory problem using oddment method
Player A\Player B | B1 | B2 | B3 |
A1 | 7 | 1 | 7 |
A2 | 9 | -1 | 1 |
A3 | 5 | 7 | 6 |
Solution:1. Saddle point testing
Players
| | | Player `B` | | |
| | | `B_1` | `B_2` | `B_3` | | |
Player `A` | `A_1` | | 7 | 1 | 7 | | |
`A_2` | | 9 | -1 | 1 | | |
`A_3` | | 5 | 7 | 6 | | |
We apply the maximin (minimax) principle to analyze the game.
| | | Player `B` | | |
| | | `B_1` | `B_2` | `B_3` | | Row Minimum |
Player `A` | `A_1` | | 7 | 1 | 7 | | `1` |
`A_2` | | 9 | -1 | 1 | | `-1` |
`A_3` | | [5] | (7) | 6 | | `[5]` |
| Column Maximum | | `9` | `(7)` | `7` | | |
Select minimum from the maximum of columns
Column MiniMax = (7)
Select maximum from the minimum of rows
Row MaxiMin = [5]
Here, Column MiniMax `!=` Row MaxiMin
`:.` This game has no saddle point.
2. Dominance rule to reduce the size of the payoff matrix
Using dominance property
| | | Player `B` | | |
| | | `B_1` | `B_2` | `B_3` | | |
Player `A` | `A_1` | | 7 | 1 | 7 | | |
`A_2` | | 9 | -1 | 1 | | |
`A_3` | | 5 | 7 | 6 | | |
Also, no course of action dominates the other
Reduced matrix is
| | | Player `B` | | |
| | | `B_1` | `B_2` | `B_3` | | |
Player `A` | `A_1` | | 7 | 1 | 7 | | |
`A_2` | | 9 | -1 | 1 | | |
`A_3` | | 5 | 7 | 6 | | |
Find column difference `C_1-C_2`, `C_2-C_3` and row difference `R_1-R_2`, `R_2-R_3` | | | Player `B` | | | |
| | | `B_1` | `B_2` | `B_3` | | `C_1-C_2` | `C_2-C_3` |
Player `A` | `A_1` | | 7 | 1 | 7 | | 6 | -6 |
`A_2` | | 9 | -1 | 1 | | 10 | -2 |
`A_3` | | 5 | 7 | 6 | | -2 | 1 |
| `R_1-R_2` | | `-2` | `2` | `6` | | | |
| `R_2-R_3` | | `4` | `-8` | `-5` | | | |
Find oddments of individual strategies using determinantsOddment for `A_1` = det `|[10,-2],[-2,1]|=|10-4|=6`
Oddment for `A_2` = det `|[6,-6],[-2,1]|=|6-12|=6`
Oddment for `A_3` = det `|[6,-6],[10,-2]|=|(-12)-(-60)|=48`
Oddment for `B_1` = det `|[2,-8],[6,-5]|=|(-10)-(-48)|=38`
Oddment for `B_2` = det `|[-2,4],[6,-5]|=|10-24|=14`
Oddment for `B_3` = det `|[-2,4],[2,-8]|=|16-8|=8`
So Oddment matrix is
| | | Player `B` | | |
| | | `B_1` | `B_2` | `B_3` | | Oddments |
Player `A` | `A_1` | | 7 | 1 | 7 | | 6 |
`A_2` | | 9 | -1 | 1 | | 6 |
`A_3` | | 5 | 7 | 6 | | 48 |
| Oddments | | `38` | `14` | `8` | | |
Sum of A Oddment `=6+6+48=60`
Sum of B Oddment `=38+14+8=60`
Here these sums are equal
Find probabilities of individual strategies`P(A_1)=6/60=1/10`
`P(A_2)=6/60=1/10`
`P(A_3)=48/60=4/5`
`P(B_1)=38/60=19/30`
`P(B_2)=14/60=7/30`
`P(B_3)=8/60=2/15`
Value of game `V=(7*6+9*6+5*48)/60`
`=336/60`
`=28/5`
Optimal strategy for `A=(1/10,1/10,4/5)`
Optimal strategy for `B=(19/30,7/30,2/15)`