Sharp asymptotics of the homogeneous quotient Hilbert–Schmidt norm

Determine the sharp asymptotics of the supremum of the squared Hilbert–Schmidt norms of compressed cross-commutators over homogeneous degree-$D$ polynomial quotient modules, including whether the normalized supremum converges to one and whether powers of a single toral linear factor are asymptotically extremal.

Background

For a homogeneous polynomial generator of degree DD, the paper proves an upper bound of 1+log(2DD)1+\log\binom{2D}{D} for the squared Hilbert–Schmidt norm of the quotient cross-commutator. The family pN=(zw)Np_N=(z-w)^N gives a lower bound of order DD and shows that no degree-independent bound exists.

The exact leading constant, extremizing generators, and stability or equality conditions remain unresolved. The problem asks whether the lower-bound family is asymptotically optimal and how the relevant Verblunsky coefficients and endpoint weights characterize extremality.

References

Theorems~\ref{thm:quotient-singular-values} and~\ref{thm:quotient-unbounded} give $D-o(D)\leq \mathfrak Q_D\leq1+\log\binom{2D}{D}$. Determine the sharp asymptotics of $\mathfrak Q_D$. In particular, is $\mathfrak Q_D/D\to1$? Are powers of a single toral linear factor asymptotically extremal, and which equality or stability conditions can be read from the Verblunsky coefficients and the endpoint weights $a_q,b_q$?

Verblunsky coefficients, CMV matrices and numerical invariants of homogeneous bidisc submodules  (2608.18456 - Lu et al., 19 Aug 2026) in Problem 2, Section 10, "Problems and further directions"