\begin{equation}
    \max_{x_c}J_c=\max_{x_c} \left( \log \frac{\exp \left(\bar r_c(x_c) / \tau \right)}{ \frac{1}{K}\sum_{k=1}^K \exp \left(\bar r_k(x_c) / \tau\right)} \right) \ ,  %
\label{eq:objective}
\end{equation}
