1. Method & Example-1
Method
2Xn Games Steps (Rule)
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Step-1:
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If this game does not have a saddle point and not reducible by the dominance method,
then first write all 2`xx`2 sub-games and find the value of each 2`xx`2 sub-games.
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Step-2:
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Find 2`xx`2 sub-game which has the lowest value and this sub-game provides the solution to the larger game.
Solve this sub-game using algebraic method.
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Example-1
1. Find Solution of game theory problem using 2Xn Games
Player A\Player B | B1 | B2 | A1 | -3 | 4 | A2 | -1 | 1 | A3 | 7 | -2 |
Solution: 1. Saddle point testing Players
| | | Player `B` | | | | | | `B_1` | `B_2` | | | Player `A` | `A_1` | | -3 | 4 | | `A_2` | | -1 | 1 | | `A_3` | | 7 | -2 | |
We apply the maximin (minimax) principle to analyze the game.
| | | Player `B` | | | | | | `B_1` | `B_2` | | Row Minimum | Player `A` | `A_1` | | -3 | (4) | | `-3` | `A_2` | | [-1] | 1 | | `[-1]` | `A_3` | | 7 | -2 | | `-2` | | Column Maximum | | `7` | `(4)` | | |
Select minimum from the maximum of columns Column MiniMax = (4)
Select maximum from the minimum of rows Row MaxiMin = [-1]
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` | | | Player `A` | `A_1` | | -3 | 4 | | `A_2` | | -1 | 1 | | `A_3` | | 7 | -2 | |
Also, no course of action dominates the other
So, we consider each 2`xx`2 sub-game and obtain their values
Players
| | | Player `B` | | | | | | `B_1` | `B_2` | | | Player `A` | `A_1` | | -3 | 4 | | `A_2` | | -1 | 1 | | `A_3` | | 7 | -2 | |
2`xx`2 sub-game : (1) Row 1, 2
| | | Player `B` | | | | | | `B_1` | `B_2` | | | Player `A` | `A_1` | | -3 | 4 | | `A_2` | | -1 | 1 | |
This game has saddle point and value of the game, `V_1` is -1
2`xx`2 sub-game : (2) Row 1, 3
| | | Player `B` | | | | | | `B_1` | `B_2` | | | Player `A` | `A_1` | | -3 | 4 | | `A_3` | | 7 | -2 | |
This game has no saddle point, so we use the algebraic method. Value of game, `V_2=(a * d - b * c)/((a + d) - (b + c))=((-3 xx -2) - (4 xx 7))/((-3 -2) - (4 +7))=(6 -28)/(-5 -11)=11/8`
2`xx`2 sub-game : (3) Row 2, 3
| | | Player `B` | | | | | | `B_1` | `B_2` | | | Player `A` | `A_2` | | -1 | 1 | | `A_3` | | 7 | -2 | |
This game has no saddle point, so we use the algebraic method. Value of game, `V_3=(a * d - b * c)/((a + d) - (b + c))=((-1 xx -2) - (1 xx 7))/((-1 -2) - (1 +7))=(2 -7)/(-3 -8)=5/11`
The 2`xx`2 sub-game with the lowest value is `-1` in (1) and hence the solution to this game provides the solution to the larger game.
Using algebraic method 1. Saddle point testing Players
| | | Player `B` | | | | | | `B_1` | `B_2` | | | Player `A` | `A_1` | | -3 | 4 | | `A_2` | | -1 | 1 | |
We apply the maximin (minimax) principle to analyze the game.
| | | Player `B` | | | | | | `B_1` | `B_2` | | Row Minimum | Player `A` | `A_1` | | -3 | 4 | | `-3` | `A_2` | | [(-1)] | 1 | | `[-1]` | | Column Maximum | | `(-1)` | `4` | | |
Select minimum from the maximum of columns Column MiniMax = (-1)
Select maximum from the minimum of rows Row MaxiMin = [-1]
Here, Column MiniMax = Row MaxiMin = -1 `:.` This game has a saddle point and value of the game is -1
This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
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