English

An arithmetic count of osculating lines

Algebraic Geometry 2025-02-07 v2

Abstract

We say that a line in Pkn+1\mathbb P^{n+1}_k is osculating to a hypersurface YY if they meet with contact order n+1n+1. When k=Ck=\mathbb C, it is known that through a fixed point of YY, there are exactly n!n! of such lines. Under some parity condition on nn and deg(Y)\mathrm{deg}(Y), we define a quadratically enriched count of these lines over any perfect field kk. The count takes values in the Grothendieck--Witt ring of quadratic forms over kk and depends linearly on deg(Y)\mathrm{deg}(Y).

Keywords

Cite

@article{arxiv.2312.12129,
  title  = {An arithmetic count of osculating lines},
  author = {Giosuè Muratore},
  journal= {arXiv preprint arXiv:2312.12129},
  year   = {2025}
}

Comments

21 pages, nyjm.albany.edu/j/2024/30-72.html

R2 v1 2026-06-28T13:56:02.380Z