Vanishing orders and zero degree Turán densities

This paper investigates the structural implications of vanishing \ell-degree Turán densities in hypergraphs, proving that for kk-uniform hypergraphs with vanishing 2-degree Turán density, a specific global vertex ordering (2-vanishing order) must exist, thereby generalizing classical results on zero Turán density and demonstrating that unlike the classical case, 2-degree Turán densities accumulate at zero.

Laihao Ding, Hong Liu, Haotian Yang2026-03-09🔢 math

Metrical Distortion, Exterior Differential and Gauss's Lemma

This paper revises Gauss's Lemma by introducing the concept of "metrical distortion" as a non-identity isometry between double tangential and tangential spaces, and concretely defines the exterior differential via covariant gradient transport to incorporate a "differential slip" representing scalar gauge theory, ultimately distinguishing between geodesically radial volume preservation (metrical distortion) and length preservation (exponential mapping) through the example of the 2-sphere.

Stephan Voellinger2026-03-09🔢 math

Characterization of Maximizers for Sums of the First Two Eigenvalues of Sturm-Liouville Operators

This paper establishes the existence and uniqueness of a non-negative, piecewise smooth, and symmetric potential in L1L^1 that maximizes the sum of the first two Dirichlet eigenvalues for Sturm-Liouville operators, demonstrating that its nonzero part is determined by the solution to the pendulum equation via measure differential equations and weak^* convergence.

Gang Meng, Yuzhou Tian, Bing Xie, Meirong Zhang2026-03-09🔢 math

STAR Beyond Diagonal RISs with Amplification: Modeling and Optimization

This paper proposes a physically consistent signal model and an alternating optimization framework for downlink sum-rate maximization in STAR beyond-diagonal RISs with per-element amplification, achieving substantial performance gains over conventional passive systems while ensuring hardware feasibility and passivity.

Chandan Kumar Sheemar, Giovanni Iacovelli, Wali Ullah Khan, George C. Alexandropoulos, Stefano Tomasin, Symeon Chatzinotas2026-03-09🔢 math

Oort's conjecture on automorphisms of generic supersingular abelian varieties

This paper proves Oort's conjecture that the automorphism group of a generic principally polarized supersingular abelian variety in characteristic pp is {±1}\{\pm 1\}, except for the specific cases of genus 2 or 3 with p=2p=2, while also providing an explicit description of the a=1a=1-locus in the corresponding Rapoport-Zink space and establishing analogous results for supersingular pp-divisible groups.

Eva Viehmann2026-03-09🔢 math