Quadratic Segre indices
Algebraic Geometry
2026-01-28 v2
Abstract
We prove that the local Euler class of a line on a degree hypersurface in projective space is given by a product of indices of Segre involutions. Segre involutions and their associated indices were first defined by Finashin and Kharlamov over the reals. Our result is valid over any perfect field of characteristic not 2 and gives an infinite family of problems in enriched enumerative geometry with a shared geometric interpretation for the local type.
Cite
@article{arxiv.2506.01547,
title = {Quadratic Segre indices},
author = {Felipe Espreafico and Stephen McKean and Sabrina Pauli},
journal= {arXiv preprint arXiv:2506.01547},
year = {2026}
}
Comments
41 pages, 2 figures. A few errors corrected, and some explanations improved. Comments welcome!