Solution
= Solution
The <van den Berg-Kesten inequality> says that for increasing cylinder events $A$ and $B$ under product bond percolation,
$$
\mathbb P_p(A\mathbin\square B)
\leq\mathbb P_p(A)\mathbb P_p(B),
$$
where $A\mathbin\square B$ is the event that $A$ and $B$ have disjoint finite witness edge sets.