English

F-pure threshold and height of quasi-homogeneous polynomials

Algebraic Geometry 2017-02-27 v1

Abstract

We consider a quasi-homogeneous polynomial fZ[x0,,xN]f \in \mathbb{Z}[x_0, \ldots, x_N] of degree ww equal to the degree of x0xNx_0 \cdots x_N and show that the FF-pure threshold of the reduction fpFp[x0,,xN]f_p \in \mathbb{F}_p[x_0, \ldots, x_N] is equal to the log canonical threshold if and only if the height of the Artin-Mazur formal group associated to HN1(X,Gm,X)H^{N-1}\left( X, {\mathbb{G}}_{m,X} \right), where XX is the hypersurface given by ff, is equal to 1. We also prove that a similar result holds for Fermat hypersurfaces of degree >N+1>N+1. Furthermore, we give examples of weighted Delsarte surfaces which show that other values of the FF-pure threshold of a quasi-homogeneous polynomial of degree ww cannot be characterized by the height.

Keywords

Cite

@article{arxiv.1702.07553,
  title  = {F-pure threshold and height of quasi-homogeneous polynomials},
  author = {Susanne Müller},
  journal= {arXiv preprint arXiv:1702.07553},
  year   = {2017}
}