Reverse martingale convergence theorem
= Reverse martingale convergence theorem
{wiki}
For a decreasing sequence of sigma-algebras $\mathcal F_n$ and an integrable random variable $X$,
$$
\mathbb E[X\mid\mathcal F_n]
\longrightarrow
\mathbb E[X\mid\bigcap_n\mathcal F_n]
$$
almost surely and in $L^1$.