Equation 18.34.759C2D7B608B5

\begin{equation} \partial _ t^ k k_{v_ t,x} =\sum _{\alpha \in \Lambda _ k}\frac{k!}{\alpha !} \mathcal T_{t,\alpha _ p}\cdots \mathcal T_{t,\alpha _1}k_{v_ t,x}. \end{equation}