\begin{equation}
\label{eq:hgcn}
\mathbf{X}^{(l+1)}=\sigma\left(\mathbf{D}_{(v)}^{-1 / 2} \mathbf{H} \mathbf{W} \mathbf{D}_{(e)}^{-1} \mathbf{H}^{\top} \mathbf{D}_{(v)}^{-1 / 2} \mathbf{X}^{(l)} \mathbf{\Theta}^{(l)}\right),
\end{equation}
