Finding ESS in pure and mixed strategies I have to find all the ESS(pure and mixed, in this game) $\left( \begin{array}{c|ccc} & A & B & C\\\ \hline A &0,0& 3,1 &0,0\\\ B &1,3& 0,0 &0,0\\\ C &0,0& 0,0 &1,1 \end{array} \right)$ It's easy to see that C is the pure ESS, but I can't find the mixed ESS

The mixed ESS plays $A$ with probability $3/4$ and $B$ with probability $1/4$.