1. Method & Example-1
Method
Step-1:
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Player A's optimal strategies `=([[1,1]] xx P_(Adj))/([[1,1]] xx P_(Adj) xx [[1],[1]]) = [[p_1,p_2]]`
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Step-2:
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Player B's optimal strategies `=([[1,1]] xx P_(Cof))/([[1,1]] xx P_(Adj) xx [[1],[1]]) = [[q_1,q_2]]`
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Step-3:
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Value of the game = (Player A's optimal strategies) `xx` (Payoff matrix P) `xx` (Player B's optimal strategies)
`V = [[p_1,p_2]] xx P xx [[q_1],[q_2]]`
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Here `P_(Cof)` = Cofactor matrix of P and `P_(Adj)` = Adjoint matrix of P
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Example-1
1. Find Solution of game theory problem using matrix method
Player A\Player B | B1 | B2 | B3 | A1 | 1 | 7 | 2 | A2 | 6 | 2 | 7 | A3 | 5 | 1 | 6 |
Solution: 1. Saddle point testing Players
| | | Player `B` | | | | | | `B_1` | `B_2` | `B_3` | | | Player `A` | `A_1` | | 1 | 7 | 2 | | `A_2` | | 6 | 2 | 7 | | `A_3` | | 5 | 1 | 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` | | 1 | 7 | 2 | | `1` | `A_2` | | (6) | [2] | 7 | | `[2]` | `A_3` | | 5 | 1 | 6 | | `1` | | Column Maximum | | `(6)` | `7` | `7` | | |
Select minimum from the maximum of columns Column MiniMax = (6)
Select maximum from the minimum of rows Row MaxiMin = [2]
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` | | 1 | 7 | 2 | | `A_2` | | 6 | 2 | 7 | | `A_3` | | 5 | 1 | 6 | |
row-3 `<=` row-2, so remove row-3
| | | Player `B` | | | | | | `B_1` | `B_2` | `B_3` | | | Player `A` | `A_1` | | 1 | 7 | 2 | | `A_2` | | 6 | 2 | 7 | |
column-3 `>=` column-1, so remove column-3
| | | Player `B` | | | | | | `B_1` | `B_2` | | | Player `A` | `A_1` | | 1 | 7 | | `A_2` | | 6 | 2 | |
reduced matrix
| | | Player `B` | | | | | | `B_1` | `B_2` | | | Player `A` | `A_1` | | 1 | 7 | | `A_2` | | 6 | 2 | |
For this reduced matrix, calculate `P_(Adj)` and `P_(Cof)`
`P_(Adj) = [[2,-7],[-6,1]]`
and `P_(Cof) = [[2,-6],[-7,1]]`
Player A's optimal strategies `=([[1,1]] xx P_(Adj))/([[1,1]] xx P_(Adj) xx [[1],[1]])`
`=([[1,1]][[2,-7],[-6,1]])/([[1,1]][[2,-7],[-6,1]][[1],[1]])`
`=([[-4,-6]])/(-10)`
`=[[2/5,3/5]]`
`p_1=2/5` and `p_2=3/5`, where `p_1` and `p_2` represent the probabilities of player A's, using his strategies `A_1` and `A_2` respectively.
Similarly, Player B's optimal strategies `=([[1,1]] xx P_(Cof))/([[1,1]] xx P_(Adj) xx [[1],[1]])`
`=([[1,1]][[2,-6],[-7,1]])/([[1,1]][[2,-7],[-6,1]][[1],[1]])`
`=([[-5,-5]])/(-10)`
`=[[1/2,1/2]]`
`q_1=1/2` and `q_2=1/2`, where `q_1` and `q_2` represent the probabilities of player B's, using his strategies `B_1` and `B_2` respectively.
Hence, Value of the game `V` = (Player A's optimal strategies) `xx` (Payoff matrix `P_(ij)`) `xx` (Player B's optimal strategies)
`V=[[2/5,3/5]][[1,7],[6,2]][[1/2],[1/2]]=4`
This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
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