Skip to Main Content


AMS eBook CollectionsOne of the world's most respected mathematical collections, available in digital format for your library or institution


Cohomology of the Moduli Space of Cubic Threefolds and Its Smooth Models

About this Title

Sebastian Casalaina-Martin, Samuel Grushevsky, Klaus Hulek and Radu Laza

Publication: Memoirs of the American Mathematical Society
Publication Year: 2023; Volume 282, Number 1395
ISBNs: 978-1-4704-6020-4 (print); 978-1-4704-7351-8 (online)
DOI: https://doi.org/10.1090/memo/1395
Published electronically: January 3, 2023

PDF View full volume as PDF

View other years and numbers:

Table of Contents

Chapters

  • 1. Introduction
  • 2. Preliminaries
  • 3. The cohomology of the Kirwan blowup, part I: equivariant cohomology of the semi-stable locus
  • 4. The cohomology of the Kirwan blowup, part II
  • 5. The intersection cohomology of the GIT moduli space $\mathcal {M}^{\operatorname {GIT}}$
  • 6. The intersection cohomology of the ball quotient
  • 7. The cohomology of the toroidal compactification
  • A. Equivariant cohomology
  • B. Stabilizers, normalizers, and fixed loci for cubic threefolds
  • C. The moduli space of cubic surfaces

Abstract

We compute and compare the (intersection) cohomology of various natural geometric compactifications of the moduli space of cubic threefolds: the GIT compactification and its Kirwan blowup, as well as the Baily–Borel and toroidal compactifications of the ball quotient model, due to Allcock–Carlson–Toledo. Our starting point is Kirwan’s method. We then follow by investigating the behavior of the cohomology under the birational maps relating the various models, using the decomposition theorem in different ways, and via a detailed study of the boundary of the ball quotient model. As an easy illustration of our methods, the simpler case of the moduli space of cubic surfaces is discussed in an appendix.

References [Enhancements On Off] (What's this?)

References