English

Multiplier ideals of normal surface singularities

Algebraic Geometry 2024-10-21 v2

Abstract

We study the multiplier ideals and the corresponding jumping numbers and multiplicities {m(c)}cR\{m(c)\}_{c\in \mathbb{R}} in the following context: (X,o)(X,o) is a complex analytic normal surface singularity, aOX,o{\mathfrak a}\subset \mathcal{O}_{X,o} is an mX,o{\mathfrak m}_{X,o}--primary ideal, ϕ:X~X\phi:\widetilde{X}\to X is a log resolution of a\mathfrak{a} such that aOX~=OX~(F)\mathfrak{a}\mathcal{O}_{\widetilde{X}}=\mathcal{O}_{\widetilde{X}}(-F), for some nonzero effective divisor FF supported on ϕ1(0)\phi^{-1}(0). We show that {m(c)}c>0\{m(c)\}_{c>0} is combinatorially computable from FF and the resolution graph Γ\Gamma of ϕ\phi, and we provide several formulae. We also extend Budur's result (valid for (X,o)=(C2,0)(X,o)=(\mathbb{C}^2,0)), which makes an identification of c[0,1]m(c)tc\sum_{c\in[0,1]}m(c)t^c with a certain Hodge spectrum. In our general case we use Hodge spectrum with coefficients in a mixed Hodge module. We show that {m(c)}c0\{m(c)\}_{c\leq 0} usually depends on the analytic type of (X,o)(X,o). However, for some distinguished analytic types we determine it concretely. E.g., when (X,o)(X,o) is weighted homogeneous (and FF is associated with the central vertex), we recover cm(c)tc\sum_cm(c)t^c from the Poincar\'e series of (X,o)(X,o) and when (X,o)(X,o) is a splice quotient then we recover cm(c)tc\sum_cm(c)t^c from the multivariable topological Poincar\'e (zeta) function of Γ\Gamma.

Keywords

Cite

@article{arxiv.2407.13413,
  title  = {Multiplier ideals of normal surface singularities},
  author = {László Koltai and Tamás László and András Némethi},
  journal= {arXiv preprint arXiv:2407.13413},
  year   = {2024}
}

Comments

23 pages, some minor corrections, list of references extended

R2 v1 2026-06-28T17:45:51.884Z