  Let $\mathcal{A}$ be an associative algebra containing the classical or
quantum universal enveloping algebra $U$ of a semi-simple complex Lie algebra.
Let $\mathcal{J}\subset \mathcal{A}$ designate the left ideal generated by
positive root vectors in $U$. We construct the reduction algebra of the pair
$(\mathcal{A},\mathcal{J})$ via the inverse Shapovalov form of $U$.
