Seminario de Geometría Algebraica

Seminario de Geometría Algebraica
2025-05-13
13:30hrs.
Giancarlo Urzúa. UC Chile
Hacking Vector Bundles 1
sala 2
2025-05-08
13:30hrs.
Giancarlo Urzúa. UC Chile
Baby: Mini Introducción a Geometría Birracional
sala 2
2025-05-06
13:30hrs.
Sid Mathur. UC Chile
Vector Bundles in Projective Spaces
sala 2
2025-04-24
13:30hrs.
Giancarlo Urzúa. UC Chile
Baby: Mmp y Curvas Racionales Con Grado Arbitrariamente Alto en Superficies K3
sala 2
2025-04-22
13:30hrs.
Yulieth Prieto. UC Chile
Transitioning to higher dimensions
sala 2
Abstract:
What is currently known? What are the main obstructions? Lagrangian fibrations in IHS varieties.
2025-04-15
13:30hrs.
Yulieth Prieto. UC Chile
Elliptic fibrations on K3 surfaces
sala 2
Abstract:
Invariants of elliptic fibrations on K3 surfaces. Applications of Torelli Theorem for the moduli of K3 surfaces admitting elliptic fibrations. Lattice-based criteria for the existence of elliptic fibrations. The Shioda formula.
2025-04-10
13:30hrs.
Sebastián Flores. UC Chile
Baby: Superficies de Tipo General a Partir de Superficies K3 y Curvas Racionales
sala 2
2025-04-08
13:30hrs.
Yulieth Prieto. UC Chile
The bilinear form of the second cohomology group and the Néron-Severi lattice
sala 2
Abstract:
Basic definition of lattices. The discriminant group. The bilinear form associated with the cohomology of a K3 surface and the abstract K3 lattice. The problem of existence, uniqueness, and embedding of lattices. The Beauville-Bogomolov form for IHS manifolds.
2025-04-03
13:30hrs.
Marcos Canedo. UC Chile
Baby: Deformaciones de Superficies Algebraicas y Obstrucciones
sala 2
2025-04-01
13:30hrs.
Yulieth Prieto. UC Chile
Automorphism Groups and Quotients
sala 2
Abstract:
Symplectic and non-symplectic. General properties of these automorphisms. Quotients of K3 surfaces by automorphisms of finite order. Applications of Torelli Theorem. Comments on the automorphism group for the Hilbert scheme of points on K3 surfaces. 
https://sites.google.com/view/yuliethprietom/teaching/seminario-puc?authuser=0
2025-03-27
13:30hrs.
Marcos Canedo. UC Chile
Baby: Superficies Singulares y No Singulares
sala 2
2025-03-25
13:30hrs.
Yulieth Prieto. UC Chile
Teorema de Torelli para superficies K3
sala 2
Abstract:
  • Torelli Theorem for K3 surfaces and its proof. Period map. Moduli of polarized K3 surfaces (the case of Kummer surfaces). Formulation of Torelli Theorem for IHS manifolds. 

2025-03-20
13:30hrs.
Marcos Canedo. UC Chile
Baby: Fracciones Continuas Negativas, Cadenas de Wahl, Fracciones del 0
sala 2
2025-03-18
13:30hrs.
Yulieth Prieto. UC Chile
K3 surfaces: definiciones y problemas
sala 2
Abstract:
K3 surfaces and their analogues in higher dimensions 

The goal of this seminar is to present the fundamental tools for formulating questions related to the study of specific geometric properties of K3 surfaces (e.g., such as automorphisms, elliptic fibrations, Shioda-Inose structures). Furthermore, it aims to explore the analogue of these tools in the context of higher-dimensional varieties, known as irreducible holomorphic symplectic (IHS) manifolds or Hyperkähler. 


https://sites.google.com/view/yuliethprietom/teaching/seminario-puc?authuser=0
2025-03-13
13:30hrs.
Giancarlo Urzúa. UC Chile
BABY: Fracciones continuas negativas en geometría birracional
sala 2
Abstract:
Será una introducción a geometría birracional de degeneraciones de superficies complejas, basado en el libro en progreso "Negative continued fractions in birational geometry: A guide to Wahl degenerations of surfaces". 

Tópicos guías:

 

1. Hirzebruch-Jung continued fractions

1.1. Basics

1.2. Wahl chains

1.3. Zero continued fractions

2. Singular and nonsingular algebraic surfaces 

2.1. Generalities on surfaces and singularities 

2.2. Cyclic quotient singularities 

2.3. T-singularities 

3. Deformations 

3.1. General basic theory for affine and proper varieties 

3.2. Q-Gorenstein deformations 

3.3. Kollár–Shepherd-Barron correspondence 

4. W-surfaces

4.1. Picard group, class group, and topology

4.2. MMP for W-surfaces I 

4.3. MMP for W-surfaces II 

5. N-resolutions

5.1. Existence and uniqueness 

5.2. Braid group action 

6. Exceptional collections of Hacking bundles 

6.1. Hacking exceptional bundles 

6.2. Hacking exceptional collections 

6.3. Exceptional collections and H.e.c.s 

 

2024-12-03
13:30hrs.
Jenia Tevelev. Umass Amherst
Deformations of the Kalck-Karmazyn Algebra via Homological Mirror Symmetry
sala 2
Abstract:
Kawamata observed that a Q-Gorenstein smoothing of a Wahl singularity gives rise to a matrix order, i.e., a 1-parameter flat degeneration of a matrix algebra. Tevelev and Urzúa later generalized this result to general smoothings of 2-dimensional cyclic quotient singularities. However, these results were proved using abstract methods of birational geometry, making explicit calculations challenging. In joint work with Yanki Lekili, we use homological mirror symmetry to derive explicit formulas for Kawamata’s matrix orders.
2024-11-26
13:30hrs.
Aníbal Aravena. Umass Amherst
Fano visitor conjecture for K3 surfaces
sala 2
Abstract:
A smooth projective variety is said to be a Fano visitor if its derived category  can be embedded into the derived category of a smooth Fano manifold. In 2011, Bondal conjetured that every smooth projective variety is a Fano visitor. In this talk, I will discuss  a proof of this conjecture for  75% fo K3 surfaces  by using the work of Bayer and Macrì, which describes the birational geometry of a moduli space of sheaves on a K3 surface  through Bridgeland stability condition, and the study of fixed locus of antysimplectic involution by Saccà, Macrì, O'Grady, and Flapan. 
 
2024-11-26
13:30hrs.
Aníbal Aravena. UC Chile
Grand Finale: Superficies de K3 y Condiciones de Estabilidad
sala 2
2024-11-21
13:30hrs.
Benjamín Maldonado. UC Chile
Baby Baby: Cocientes de Variedades Afines Por Grupos Finitos
sala 2
2024-11-19
13:30hrs.
Aníbal Aravena. Umass Amherst
Geometría Birracional de Espacios de Moduli
sala 2