Singularity categories of rational double points in arbitrary characteristic
Abstract
We establish a one-to-one correspondence between the singularity categories of rational double points and the simply-laced Dynkin graphs in arbitrary characteristic. This correspondence is well-known in characteristic zero since the rational double points are quotient singularities in characteristic zero whereas not necessarily in positive characteristic. Considering some rational double points are not taut in characteristic two, three or five, we can see there exist two rational double points which are not analytically isomorphic but whose singularity categories are triangulated equivalent. As an application, we construct a counter-example in positive characteristic of a theorem of Hua and Keller: the dg singularity category of a hypersurface singularity determines its Tyurina algebra.
Cite
@article{arxiv.2408.02532,
title = {Singularity categories of rational double points in arbitrary characteristic},
author = {Yuta Takashima and Hokuto Uehara},
journal= {arXiv preprint arXiv:2408.02532},
year = {2024}
}
Comments
We claim the singularity category of a RDP is standard by showing the corresponding mesh algebra and Auslander algebra have the same dimension. The crucial step is Remark 2.8. However, Hideto Asashiba and Osamu Iyama have pointed out that in Remark 2.8 there is no surjection from the mesh algebra to the Auslander algebra in general. Hence we need to construct a surjection or take another strategy