Deterministic evaluation and holonomic structure for moderate sample sizes

Determine, for each fixed sample size n, the order of a linear differential equation with polynomial coefficients satisfied by the Jarque–Bera density f_{JB_n}(x), and determine whether this equation is ever of hypergeometric (first-order recurrence) type, thereby enabling deterministic evaluation of the distribution function by the holonomic gradient method.

Background

The paper represents the finite-sample Jarque–Bera distribution through period integrals of algebraic families. This structure suggests that f_{JB_n} may be holonomic, meaning that it satisfies a linear differential equation in the statistic x with polynomial coefficients. If such equations were available, the corresponding moments would typically satisfy polynomial-coefficient recurrences in the moment order.

The authors propose determining the differential-equation order as a function of n and deciding whether a hypergeometric reduction occurs. These results could support deterministic computation of the Jarque–Bera distribution function through the holonomic gradient method, replacing simulation for moderate sample sizes and improving finite-sample calibration.

References

Determine the order of the equation as a function of $n$ and whether it is ever of hypergeometric (first-order recurrence) type.

— Exact finite-sample geometry of the Jarque-Bera statistic: support, discriminants and elliptic integrals  (2609.29976 - Lawford, 24 Sep 2026) in Section 6, “Discussion and open problems”; Open problem “Deterministic evaluation for moderate n,” label op:holonomic

For $n\ge6$ the minimum set ${S_n=0,K_n=3}$ has positive dimension, so the stationary points are no longer isolated, and the remaining stationary points have not been classified. For the joint density the classification is open beyond the cases treated here: for $n=4$ the singularities are inverse-square-root at the edges of the support, and for $n=5$ the density jumps at the boundary and is logarithmic along interior curves (Section~\ref{sec:n5}).

— Exact finite-sample geometry of the Jarque-Bera statistic: support, discriminants and elliptic integrals  (2609.29976 - Lawford, 24 Sep 2026) in Section 6, “Discussion and open problems”; Open problem “Singularity classification,” label op:sing