$$\pi__(a|s) =
\left{
\begin{array}{ll}
\displaystyle 1 & \textrm{if}\ a=\arg\max_{a\in A}q__(s,a)\\
\displaystyle 0 & \textrm{otherwise}
\end{array}
\right.$$
$$\pi__(a|s) =
\left{
\begin{array}{ll}
\displaystyle 1 & \textrm{if}\ a=\arg\max_{a\in A}q__(s,a)\\
\displaystyle 0 & \textrm{otherwise}
\end{array}
\right.
$$
$$
\pi__(a|s) =
\left{
\begin{array}{ll}
\displaystyle 1 & \textrm{if}\ a=\arg\max_{a\in A}q__(s,a)\\
\displaystyle 0 & \textrm{otherwise}
\end{array}
\right.
$$
$$\pi__(a|s) = \left{ \begin{array}{ll} \displaystyle 1 & \textrm{if}\ a=\arg\max_{a\in A}q__(s,a)\ \displaystyle 0 & \textrm{otherwise} \end{array}\right.$$
inline: $\pi_(a|s) = \left{ \begin{array}{ll} \displaystyle 1 & \textrm{if}\ a=\arg\max_{a\in A}q_(s,a)\ \displaystyle 0 & \textrm{otherwise} \end{array}\right.$