Blowups, Gale duality, and moduli spaces

Fuente: arXiv
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Autori principali: Araujo, Carolina, Castravet, Ana-Maria, Kaur, Inder, Martinelli, Diletta
Natura: Preprint
Pubblicazione: 2026
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author Araujo, Carolina
Castravet, Ana-Maria
Kaur, Inder
Martinelli, Diletta
author_facet Araujo, Carolina
Castravet, Ana-Maria
Kaur, Inder
Martinelli, Diletta
contents The goal of this paper is to describe the birational geometry of the blowup of $\mathbb{P}^n$ at $n+4$ points in very general position. To achieve this, we follow an idea of Mukai and explore a special instance of Gale duality, namely, a correspondence between configurations of $n+4$ points in the projective spaces $\mathbb{P}^n$ and $\mathbb{P}^2$. We first prove that the blowup $X$ of $\mathbb{P}^n$ at $n+4$ general points is isomorphic to a certain Gieseker moduli space of rank $2$ vector bundles on the surface $S$ obtained by blowing up $\mathbb{P}^2$ at the $n+4$ Gale dual points. We then study the variation of these moduli spaces as we vary the polarization $L$ on $S$, and translate this variation into a partial Mori chamber decomposition of $\overline{Eff}(X)$, describing to some extent the birational geometry of $X$.
format Preprint
id arxiv_https___arxiv_org_abs_2605_27152
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Blowups, Gale duality, and moduli spaces
Araujo, Carolina
Castravet, Ana-Maria
Kaur, Inder
Martinelli, Diletta
Algebraic Geometry
The goal of this paper is to describe the birational geometry of the blowup of $\mathbb{P}^n$ at $n+4$ points in very general position. To achieve this, we follow an idea of Mukai and explore a special instance of Gale duality, namely, a correspondence between configurations of $n+4$ points in the projective spaces $\mathbb{P}^n$ and $\mathbb{P}^2$. We first prove that the blowup $X$ of $\mathbb{P}^n$ at $n+4$ general points is isomorphic to a certain Gieseker moduli space of rank $2$ vector bundles on the surface $S$ obtained by blowing up $\mathbb{P}^2$ at the $n+4$ Gale dual points. We then study the variation of these moduli spaces as we vary the polarization $L$ on $S$, and translate this variation into a partial Mori chamber decomposition of $\overline{Eff}(X)$, describing to some extent the birational geometry of $X$.
title Blowups, Gale duality, and moduli spaces
topic Algebraic Geometry
url https://arxiv.org/abs/2605.27152