Nash equilibrium of mixed strategies

71 Views Asked by At

I have found 2 pure Nash equilibria in the following game which are (Y,B) & (Z,C)

A B C
X 6 , 0 0 , 3 1 , 8
Y 3 , 4 1 , 5 1 , 3
Z 7 , 2 0 , 1 2 , 3

I am looking for mixed strategy Nash Equilibria.

Let A probability be $p_1$, B probability be $p_2$, and C probability be $1−p_1−p_2$.

$ EU(X)=6p_1+1-p_1-p_2 = 5p_1-p_2+1 $

$ EU(Y)=3p_1+p_2+1-p_1-p_2 = 2p_1+1 $

$ EU(Z)=7p_1+2-2p_1-2p_2=5p_1-2p_2+2$

From these 3 equations I get:

$p_1=1/3, p_2=1$ which does not make sense as a probability distribution.

If I follow the same approach for the other player:

Let X probability be $q_1$, Y probability be $q_2$, and Z probability be $1−q_1−q_2$.

$EU(A)= 4q_2+2-2q_1-2q_2=-2q_1+2q_2+2$

$EU(B)= 3q_1+5q_2+1-q_1-q_2=2q_1+4q_2+1$

$EU(C)= 8q_1+3q_2+3-3q_1-3q_2 = 5q_1+3$

Form these 3 equations I get:

$q_1=0, q_2=0.5$

I am not sure how to interpret these results. Is there a Nash equilibrium of mixed strategies here?