Math Calendar

Tuesday, February 11, 2025
15:00-16:30
HFG 707
Category Theory Seminar
Remy van Dobben de Bruyn - Pretopoi and profinite Galois theory
Grothendieck's Galois theory sets up an analogy between covering space theory in topology and the Galois theory of fields. After briefly explaining the historical motivation, I will explain an extension of these results to pretopoi with a finite jointly conservative family of fibre functors (models). This gives a quick proof of a (simplified but more computationally feasible) version of the exodromy theorem of Barwick–Glasman–Haine from 2018. Time permitting, I will also sketch the connection to Makkai's strong conceptual completeness theorem and Lurie's ultracategories.
Wednesday, February 12, 2025
13:30-15:30
HFG 707
Trace Methods and Computations Seminar
THH and Integral p-adic Hodge theory 2 - Vignesh Subramanian

This seminarwill explore important themes in modern homotopy theory, focusing onTopological Hochschild Homology (THH), Topological Cyclic Homology (TC), andtheir applications in algebraic K-theory, with a special emphasis on tracemethods.

Friday, February 14, 2025
13:00-17:00
Minnaert 2.08
Arakelov Theory Seminar
Series of talks for the Learning seminar on Arakelov theory, with a view towards a proof of Uniform Mordell-Lang.

Speakers:
1. Soumya Sankar: Overview of seminar
2. Justin Uhlemann: Introduction to higher dimensional Arakelov theory - I
3. Robin de Jong: Introduction to higher dimensional Arakelov theory - II


See https://www.rationalpoints.nl/events-2/learning-seminar-on-arakelov-theory/ for more details.
15:00-17:00
HFG 707
Friday Fish - Differentiable Stacks I
Bas Wensink - Stack of Triangles
In this first talk on differentiable stack, we will return to a mathematical object from high school mathematics: the triangle. Classifying triangles and continuous families of triangles moves us into the world of stacks, and will provide us with the first example of a stack. This gives us a concrete example in which we can see the concepts that will later play a role in the discussion of general differentiable stacks.
Tuesday, February 18, 2025
13:30-14:30
Min 014
AG Seminar
Sun Woo Park (MPIM Bonn) on "Rank growth of elliptic curves over S3 extensions with fixed quadratic resolvents"
Abstract: In a joint work with Daniel Keliher, we study the probability with which an elliptic curve, subject to some technical conditions, gains rank upon base extension to families of S3 cubic extensions with a fixed quadratic resolvent field, all three types of fields of which are subject to some mild technical conditions. We determine the distribution (under a non-standard ordering) of Selmer ranks of an auxiliary abelian variety associated to the elliptic curve and cubic extensions by adapting previous studies by Klagsbrun, Mazur, and Rubin. One corollary of this distribution is that the elliptic curve gains rank by at most one upon base change to cubic extensions with probability at least 31.95%.
16:00-17:00
KBG Pangea
UGC colloquium
András Vasy (Stanford University) - Global analysis via microlocal tools
In this lecture I will describe a microlocal (or phase space based) framework for the Fredholm (invertibility up to finite rank obstacles) analysis of non-elliptic problems both on manifolds without boundary and manifolds with boundary (or corners). Examples in which such a framework (or a similar framework) has recently been useful include wave propagation on black hole spacetimes, which is a key analytic ingredient for showing the stability of black holes, analysis of the resolvent of the generator of the flow for dynamical systems, which is the key tool for the analysis of the Ruelle zeta function, and Feynman propagators in quantum field theory, which are useful for analysis of the spectral zeta function on Lorentzian spacetimes. The speaker’s contributions to this are partly joint work with collaborators: Nguyen Viet Dang, Jesse Gell-Redman, Nick Haber, Dietrich Haefner, Peter Hintz and Michal Wrochna.

UGC colloquium webpage https://utrechtgeometrycentre.nl/ugc-seminar/
Wednesday, February 19, 2025
13:30-15:30
HFG 707
Trace Methods and Computations Seminar
Prismatic Cohomology of Z and l - Gijs Heuts

This seminarwill explore important themes in modern homotopy theory, focusing onTopological Hochschild Homology (THH), Topological Cyclic Homology (TC), andtheir applications in algebraic K-theory, with a special emphasis on tracemethods.

Thursday, February 20, 2025
12:00-14:00
HFG 707
Friday Fish
Jaime Pedregal Pastor - Differentiable Stacks II
TBA
13:00-14:00
HFG611
Applied Mathematics Seminar -- Sophia Münker (RWTH Aachen) Solving Forward and Inverse Problems in Stochastic Reaction Networks via Markovian Projection

A Stochastic Reaction Network (SRN) is a continuous-time, discrete-space Markov chain, which models the random interaction of d species through reactions, commonly applied in (bio-)chemical systems. Our special interest lays in estimating statistical quantities and filtering in high dimensional SRNs (i.e., in systems with many species, in which d >> 1). Traditional methods like Monte Carlo estimators, solving filtering equations, solving the chemical master equations or the Kolmogorov backward equations become computationally expensive in such scenarios. To address the curse of dimensionality, we propose the Markovian Projection (MP) technique [1] to reduce the SRN to a lower-dimensional SRN (called MP-SRN) while preserving the marginal distribution of the original high-dimensional system. In this talk, we explore how MP can be used to derive an efficient importance sampling scheme for estimating rare event probabilities. We also explore how MP can be applied in filtering for deriving the distribution of unobserved species conditioned on a sample path of observed species.

 

[1] Ben Hammouda, C., Ben Rached, N., Tempone, R., & Wiechert, S. (2024). Automated importance sampling via optimal control for stochastic reaction networks: A Markovian projection-based approach. Journal of Computational and Applied Mathematics, 446, 115853.

Tuesday, February 25, 2025
13:30-14:30
DDW 136
AG Seminar
Jan Stienstra (Utrecht University) on "the transcendental part of K3 surfaces associated with 3D Fano polytopes"

Abstract: Up to affine transformations over Z there are 18 different 3D Fano polytopes. The set of vertices of such a polytope is a subset of Z^3 which can be used as exponents for a Laurent polynomial. The surface in P^3 defined by the homogenization of such a Laurent polynomial is a quartic K3 surface. Varying the coefficients of the Laurent polynomial yields a family of K3 surfaces. The aim of the talk is to demonstrate how the Gelfand-Kapranov-Zelevinsky hypergeometric system associated with V  and results on Mirror Symmetry for lattice polarized K3 surfaces lead to simple elegant expressions for the transcendental periods as functions of the coefficients of the Laurent polynomial.

Wednesday, February 26, 2025
13:30-15:30
HFG 707
Trace Methods and Computations Seminar
Syntomic Cohomology of Z and l - Ryan Quinn

This seminarwill explore important themes in modern homotopy theory, focusing onTopological Hochschild Homology (THH), Topological Cyclic Homology (TC), andtheir applications in algebraic K-theory, with a special emphasis on tracemethods.

Thursday, February 27, 2025
13:00-14:00
HFG611
Applied Mathematics Seminar -- Florian Wagener (UvA)
Friday, February 28, 2025
15:00-17:00
HFG 707
Friday Fish
Douwe Hoekstra - Differentiable Stacks III
TBA
Monday, March 3, 2025
11:15-13:00
HFG 6.11
Teaching staff meeting
Tuesday, March 4, 2025
13:30-14:30
Min 013
AG Seminar
Ekin Ozman (U. of Groningen)
16:00-17:00
HFG 611
MI talk
Mar Curcó-Iranzo - TBA
Wednesday, March 5, 2025
13:30-15:30
HFG 707
Trace Methods and Computations Seminar
Dundas - McCarthy Theorem - Max Blans

This seminarwill explore important themes in modern homotopy theory, focusing onTopological Hochschild Homology (THH), Topological Cyclic Homology (TC), andtheir applications in algebraic K-theory, with a special emphasis on tracemethods.

Monday, March 10, 2025
16:15-17:15
Academy Building
Inaugural address
Daniel Dadush
Tuesday, March 11, 2025
13:30-14:30
HFG 707
AG Seminar
Thilo Baumann (University of Luxembourg)
Wednesday, March 12, 2025
13:30-15:30
HFG 707
Trace Methods and Computations Seminar
Redshift for Lubin - Tate Theory - Maite Carli

This seminarwill explore important themes in modern homotopy theory, focusing onTopological Hochschild Homology (THH), Topological Cyclic Homology (TC), andtheir applications in algebraic K-theory, with a special emphasis on tracemethods.

Friday, March 14, 2025
15:00-17:00
HFG 707
Friday Fish
Sven Holtrop - Differentiable Stacks IV
TBA
Monday, March 17, 2025
15:00-17:00
Mezzanine
Teaching staff meeting
Tuesday, March 18, 2025
13:30-14:30
DDW 136
AG Seminar
Lara Vicino (U. of Groningen)
Wednesday, March 19, 2025
13:30-15:30
HFG 707
Trace Methods and Computations Seminar
Land-Tamme and Purity in Localized K-Theory - Miguel Lourenço Henriques Barata

This seminarwill explore important themes in modern homotopy theory, focusing onTopological Hochschild Homology (THH), Topological Cyclic Homology (TC), andtheir applications in algebraic K-theory, with a special emphasis on tracemethods.

Thursday, March 20, 2025
13:00-14:00
HFG 611
Applied Mathematics Seminar -- Satoshi Fukuda (Bocconi University)
Tuesday, March 25, 2025
13:30-14:30
Min 207
AG Seminar
Wednesday, March 26, 2025
13:30-15:30
HFG 707
Trace Methods and Computations Seminar
Chromatic Localizing Invariants and Descent - Marco Nervo

This seminarwill explore important themes in modern homotopy theory, focusing onTopological Hochschild Homology (THH), Topological Cyclic Homology (TC), andtheir applications in algebraic K-theory, with a special emphasis on tracemethods.

Tuesday, April 1, 2025
13:30-14:30
Min 014
AG Seminar
Thursday, April 3, 2025
13:00-14:00
Applied mathematics seminar Matteo d'Achille (U Paris Saclay)
Monday, April 7, 2025
12:00-13:00
Bring Your Own Lunch
Tuesday, April 8, 2025
13:30-14:30
Min 014
AG Seminar
Tuesday, April 15, 2025
13:30-14:30
Min 014
AG Seminar
Tuesday, April 22, 2025
10:00-11:00
HFG 707
AG Seminar
Thursday, April 24, 2025
13:00-14:00
Alef Sterk (RUG) on "Extremes in dynamical systems
max-stable and max-semistable laws"

Title:
Extremes in dynamical systems: max-stable and max-semistable laws

Abstract:
Extreme value theory for chaotic, deterministic dynamical systems is a rapidly expanding area of research. Given a dynamical system and a real-valued observable defined on its state space, extreme value theory studies the limit probabilistic laws for asymptotically large values attained by the observable along orbits of the system. Under suitable mixing conditions the extreme value laws are the same as those for stochastic processes of i.i.d. random variables.

Max-stable laws typically arise for probability distributions with regularly varying tails. However, in the context of dynamical systems, where the underlying invariant measure can be irregular, max-semistable distributions also have a natural place in studying extremal behaviour. In this talk I will first discuss a family of autoregressive processes with marginal distributions resembling the Cantor function. The resulting extreme value law can be proven to be a max-semistable distribution. Alternatively, we can describe the autoregressive process in terms of an iterated map with an invariant measure. Further examples of extreme value laws in dynamical systems are discussed as well.

Tuesday, April 29, 2025
10:00-11:00
HFG 707
AG Seminar
Shizang Li (Chinese Academy of Sciences)
Tuesday, May 6, 2025
10:00-11:00
HFG 707
AG Seminar
Monday, May 12, 2025
12:00-13:00
Bring Your Own Lunch
Tuesday, May 13, 2025
10:00-11:00
HFG 707
AG Seminar
Tuesday, May 20, 2025
10:00-11:00
HFG 707
AG Seminar
Tuesday, May 27, 2025
10:00-11:00
HFG 707
AG Seminar
Tuesday, June 3, 2025
10:00-11:00
HFG 707
AG Seminar
Tuesday, June 10, 2025
10:00-11:00
HFG 707
AG Seminar
Monday, June 16, 2025
12:00-13:00
Bring Your Own Lunch
Tuesday, June 17, 2025
10:00-11:00
HFG 707
AG Seminar
Tuesday, June 24, 2025
10:00-11:00
HFG 707
AG Seminar
Giuseppe Ancona (IRMA Strasbourg)