Stacks and Moduli
                                                                (PhD course)



Preliminary meeting:
Thursday February 17th, Aula M2 (or email me to connect by teams).
The course will then be held in a weekly basis in the period March-May.

Preliminary schedule: thursdays at 16:00, room M1 (or at teams)

The aim of the course is to give an introduction to the theory of algebraic stacks, focusing on its application to moduli theory.
We start by giving motivation and an overview of the program, which will follow mostly Jarod Alper’s  Notes on Stacks and moduli.
According to the interests of participants, further topics can be covered in the last part of the course.
The course will be mostly covered by lectures from participants, according to the program and references for each lecture.

1. Program
• Motivation and overview of the program. Guiding examples: the moduli spaces of curves and the moduli spaces of vector bundles on a curve.
• Basics on category theory. Sheaves and Grothendieck topologies.
• Groupoids and pre-stacks.
• Stacks
• Algebraic spaces and algebraic stacks
• Geometric properties of algebraic stacks
• Characterization of Deligne-Mumford stacks
• Geometry of Deligne-Mumford stacks
• Existence of coarse and good moduli spaces
• The moduli stack of curves
• Stacks on different geometric contexts (topological stacks, cone stacks, etc)

Meetings
(notes are available at teams)
•  1. (17/02/2022): program and outline
2. (03/03/2022): Background and motivation. Moduli functors. Examples. (Margarida)
3. (10/03/2022): Sites and Grothendieck topologies. (Ismaele Vanni, Sapienza).
• 4. (17/03/2022): Pseudofunctors and Prestacks. (Ismaele Vanni, Sapienza)
• 5. (24/03/2022): Stacks, descent and examples, I. (Davide Gori, Sapienza)
• 6. (31/03/2022): Stacks, descent and examples, II. (Davide Gori, Sapienza)
• 7. (07/04/2022): Hilbert and Quot schemes. (Simon Schirren, Roma Tre)
• 8. (21/04/2022): Algebraic Stacks. (Roberto Vacca, Tor Vergata)
• 9. (05/05/2022): Algebraic Stacks II and Deligne Mumford stacks I. (Roberto Vacca and Nelson Alvarado, Tor Vergata)
• 10. (11/05/2022): Deligne Mumford stacks II. (Nelson Alvarado, Tor Vergata)
• 11. (18/05/2022): Equivalence Relations and groupoids of schemes. (Luca Casarin, Sapienza)











2. References
(1) Notes on stacks and moduli, Jarod Alper
(2) Champs alg ́ebriques, Laumon and Moret-Bailly
(3) Notes on Grothendieck topologies, fibered categories and descent
theory, Vistoli
(4) Algebraic spaces and stacks, Olsson
(5) The Stacks Project
(6) Lecture notes on moduli theory, Halpern-Leistner
(7)
Existence of good moduli spaces for stacks, Alper, Halpern-Leistner, Heinloth
(8) The irreducibility of the space of curves of given genus, Deligne and Mumford
(9) Moduli of Curves, Harris and Morrison
(10) Projectivity of complete moduli, Kollár