\begin{table}[!ht]
    \centering
    \caption{\ourmethod's performance w.r.t. the number iterations $L^y$ to update rating prototypes.}
    \label{tab:rating_iter}
    % \small
    \scalebox{0.86}{
    \begin{tabular}{c
                    cc
                    cc
                    cc
                    cc}
        \toprule
        \multirow{3}{*}{\bm{$L^y$}} & \multicolumn{2}{c}{\textbf{CiteULike-a}} & \multicolumn{2}{c}{\textbf{Cell Phones}} & \multicolumn{2}{c}{\textbf{Video Games}} & \multicolumn{2}{c}{\textbf{MovieLens}}\\
        \cmidrule(lr){2-3}\cmidrule(lr){4-5}\cmidrule(lr){6-7}\cmidrule(lr){8-9}
        & R@10 & N@10 & R@10 & N@10 & R@10 & N@10 & R@10 & N@10\\
        \midrule
        1 & 23.62 & 24.33 & 6.19 & 5.03 & 8.41 & 5.42 & 14.12 & 12.84\\
        2 & 24.17 & \textbf{24.70} & 6.39 & 5.12 & 8.92 & 5.76 & 14.09 & 12.75\\
        3 & \textbf{24.20} & 24.57 & 6.51 & 5.22 & \textbf{8.95} & \textbf{5.78} & \textbf{14.35} & \textbf{13.14}\\
        4 & 23.78 & 24.28 & \textbf{6.66} & \textbf{5.35} & 8.79 & 5.68 & 14.08 & 12.90\\
         \bottomrule
    \end{tabular}
    }
\end{table}