Relationship between delta exponential and nabla exponential
From timescalewiki
Theorem: Let $p \in \mathcal{R}$ and $t,s \in \mathbb{T}$, then the following formula holds: $$\left( \dfrac{1}{e_p(\cdot,s)} \right)^{\Delta} = -\dfrac{p(t)}{e_p^{\sigma}(\cdot,s)}.$$
Proof: █
