English

$\beta$-density function on the class group of projective toric varieties

Commutative Algebra 2022-11-08 v2 Algebraic Geometry

Abstract

We prove the existence of a compactly supported, continuous (except at finitely many points) function gI,m:[0,)Rg_{I, {\bf m}}: [0, \infty)\longrightarrow \mathbb{R} for all monomial prime ideals II of RR of height one where (R,m)(R, {\bf m}) is the homogeneous coordinate ring associated to a projectively normal toric pair (X,D)(X, D), such that 0gI,m(λ)dλ=β(I,m),\int_{0}^{\infty}g_{I, {\bf m}}(\lambda)d\lambda=\beta(I, {\bf m}), where β(I,m)\beta(I, {\bf m}) is the second coefficient of the Hilbert-Kunz function of II with respect to the maximal ideal m{\bf m}, as proved by Huneke-McDermott-Monsky \cite{HMM2004}. Using the above result, for standard graded normal affine monoid rings we give a complete description of the class map τm:Cl(R)R\tau_{{\bf m}}:\text{Cl}(R)\longrightarrow \mathbb{R} introduced in \cite{HMM2004} to prove the existence of the second coefficient of the Hilbert-Kunz function. Moreover, we show the function gI,mg_{I, {\bf m}} is multiplicative on Segre products with the expression involving the first two coefficients of the Hilbert polynomial of the rings and the ideals. \keywords{coefficients of Hilbert-Kunz function\and projective toric variety\and Hilbert-Kunz density function\and β\beta-density function\and monomial prime ideal of height one.}

Keywords

Cite

@article{arxiv.2002.01677,
  title  = {$\beta$-density function on the class group of projective toric varieties},
  author = {Mandira Mondal},
  journal= {arXiv preprint arXiv:2002.01677},
  year   = {2022}
}

Comments

21 pages

R2 v1 2026-06-23T13:31:39.792Z