Best Response.md

A stratergy $s_i$ is the best response to the startergies of all other players, $s_{-i}$ if $$u_i(s_i,s_{-i})\ge u_i(s_i',s_{-i})$$ for all $s_i'\in S_i$. The set of all the best responses of player $i$ given $s_{-i}$ to be denoted $B_i(s_{-i})$

Never best response (NBR)

$s_i\in S_i$ will be NBR if $$s_i\notin B_i(s_{-i})$$ for all $s_{-i}\in S_{-i}$