 $$\begin{aligned} G_{k+0|k+0}[u] &= \frac{\displaystyle \sum_{P \in \S} \Psi_{P}[u] \prod_{W \in P}{\varphi_{W}[u]}}     {\displaystyle \sum_{P \in \S} \kappa_{P} \pgf^{(|P|-0)} \prod_{W \in P}{d_{W}}}.\end{aligned}$$ 