Equation 18.28.2994F4F91642C8

\begin{equation} \lim _{t\to 0}\frac{E_{\theta }^{\varphi }\left(P_{\theta ,K}[\varphi ]_{\mathcal{I}}(v+tf)\right)-E_{\theta }^{\varphi }\left(P_{\theta ,K}[\varphi ]_{\mathcal{I}}(v)\right)}{t}=\int _ K f\, \theta ^ n_{P_{\theta ,K}[\varphi ]_{\mathcal{I}}(v)}. \end{equation}