English

A moduli scheme parametrizing blowups of smooth projective surfaces

Algebraic Geometry 2020-06-22 v1

Abstract

We construct a moduli scheme F[n]F[n] that parametrizes tuples (S1,S2,,Sn+1,p1,p2,,pn)(S_1, S_2, \dots, S_{n+1}, p_1, p_2, \dots, p_n) in which S1S_1 is a fixed smooth surface over Spec R\text{Spec } R and Si+1S_{i+1} is the blowup of SiS_i at a point pip_i, 1in\forall 1\leq i\leq n. We show that this moduli scheme is smooth and projective. We prove that F[n]F[n] has smooth divisors Di,j(n)D_{i,j}^{(n)}, 1i<jn\forall 1\leq i<j\leq n, which correspond to tuples that map pjpip_j\mapsto p_i under the projection morphism SjSiS_j\to S_i. When R=kR=k is an algebraically closed field, we demonstrate that the Chow ring A(F[n])\mathbb{A}^*(F[n]) is generated by these divisors over A(S1n)\mathbb{A}^*(S_1^n). We end by giving a precise description of A(F[n])\mathbb{A}^*(F[n]) when S1S_1 is a complex rational surface.

Keywords

Cite

@article{arxiv.2006.10844,
  title  = {A moduli scheme parametrizing blowups of smooth projective surfaces},
  author = {Monica Marinescu},
  journal= {arXiv preprint arXiv:2006.10844},
  year   = {2020}
}
R2 v1 2026-06-23T16:26:59.868Z