Solution (source code)

= Solution

The same one-sided proxy $V^+\leq1$ lets <Talagrand's one-sided bounded differences inequality> control the opposite deviation:
$$
\mathbb P(Z-\mathbb EZ\leq-t)\leq e^{-t^2/2}.
$$
The variance estimate in part b verifies the finite-variance hypothesis in formulations of Talagrand's inequality that state it explicitly.