Equation 13.13.54A9866D01984D

\begin{equation} \mathds {1}_{\{ \varphi =f_ i\} }\, \omega ^ n_\varphi = \mathds {1}_{\{ \varphi =f_ i\} }\, \omega ^ n_{f_ i},\qquad i\in \{ 1,2\} . \end{equation}