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Autumn Semester 2026

Date / Time Speaker Title Location
16 September 2026
13:30-15:00 		Prof. Dr. Joachim Jelisiejew
University of Warsaw
Details

Algebraic Geometry and Moduli Seminar

Title Concise secant varieties and what they are good for?
Speaker, Affiliation Prof. Dr. Joachim Jelisiejew, University of Warsaw
Date, Time 16 September 2026, 13:30-15:00
Location HG G 43
Abstract Tensors, or multilinear maps, are well-known classically, but relatively isolated from modern algebraic geometry. This is hopefully about to change. In the talk I will illustrate this new bridge and its benefits also for alg.geo. Some numbers, such as 588224, 161914176, or 20636043486 may appear. This is a joint work with Jakub Jagiella.
Concise secant varieties and what they are good for?read_more
HG G 43
* 18 September 2026
16:00-17:30 		Prof. Dr. Aaron Pixton
University of Michigan
Details

Algebraic Geometry and Moduli Seminar

Title The tautological ring of M25 is not Gorenstein
Speaker, Affiliation Prof. Dr. Aaron Pixton, University of Michigan
Date, Time 18 September 2026, 16:00-17:30
Location HG G 43
Zoom
The tautological ring of M25 is not Gorenstein
HG G 43
Zoom
23 September 2026
13:30-15:00 		Jeremy Feusi
ETH Zürich
Details

Algebraic Geometry and Moduli Seminar

Title Cycles on the moduli space of vector bundles on curves
Speaker, Affiliation Jeremy Feusi, ETH Zürich
Date, Time 23 September 2026, 13:30-15:00
Location HG G 43
Cycles on the moduli space of vector bundles on curves
HG G 43
* 25 September 2026
16:00-17:30 		Benjamin Ellis-Bloor
Northwestern University
Details

Algebraic Geometry and Moduli Seminar

Title Cobordism and the moduli of curves
Speaker, Affiliation Benjamin Ellis-Bloor, Northwestern University
Date, Time 25 September 2026, 16:00-17:30
Location HG G 43
Zoom
Abstract I will discuss the problem of expressing the cobordism class of Mbar_{0,n} as a polynomial in generators of the cobordism ring. With rational coefficients, a method was given by Coates and Givental. With integer coefficients, we will get a recursion by lifting the string equation, introduced by Witten, to algebraic cobordism in genus 0. This recovers known closed formulas for invariants of Mbar_{0,n} such as the Poincaré polynomials, and gives new closed formulas for invariants such as certain twists of the chi_y-genus. I will also explain how equivariant localization in cobordism can alternatively be used, and the outlook in higher genus.
Cobordism and the moduli of curvesread_more
HG G 43
Zoom
2 October 2026
16:00-17:30 		Prof. Dr. Ignacio Barros
University of Antwerp
Details

Algebraic Geometry and Moduli Seminar

Title Euler pairing and the tautological ring of moduli spaces of K3 surfaces
Speaker, Affiliation Prof. Dr. Ignacio Barros, University of Antwerp
Date, Time 2 October 2026, 16:00-17:30
Location HG G 43
Abstract I will present work in progress on a Lefschetz-type structure on the subring in Chow generated by special cycles. In particular, we can relate the kernel of the Lefschetz operator to the vanishing of certain L-functions and obtain lower bounds for the rank of the space of tautological cycles of degree up to 16. This is very much "in progress" and all human-generated, so there will be some discussion, questions, and confusion. It is all joint work with Laure Flapan and Riccardo Zuffetti.
Euler pairing and the tautological ring of moduli spaces of K3 surfacesread_more
HG G 43
7 October 2026
13:30-15:00 		Dr. Denis Nesterov
ETH Zürich
Details

Algebraic Geometry and Moduli Seminar

Title Wall-crossing in Gromov–Witten theory I
Speaker, Affiliation Dr. Denis Nesterov, ETH Zürich
Date, Time 7 October 2026, 13:30-15:00
Location HG G 43
Abstract Moduli spaces often admit several natural compactifications. The comparison of different compactifications is referred to as wall-crossing. Some compactifications are simpler than others, making wall-crossing one of the most powerful established techniques, for example, in the study of moduli spaces of sheaves. I will discuss wall-crossing phenomena for moduli spaces of maps (Gromov–Witten theory) and other related spaces. The first glimpses of wall-crossing in Gromov–Witten theory go back to its beginnings, namely to Givental’s proof of mirror symmetry for the quintic in 1990s. Later, independently of Givental’s work, Manin and Bayer were the first to explore the idea of wall-crossing in the setting of maps, extending Hassett’s ideas on weighted marked curves. Only with the work of Ciocan-Fontanine, Kim, and Maulik from 2010s, which in turn builds on the work of many others, did it become possible to exploit different compactifications of moduli spaces of maps with considerable flexibility for GIT quotients, thereby revealing Givental’s proof as a wall-crossing calculation. Zhou then made the next major step by proving the Ciocan-Fontanine–Kim wall-crossing formulas for GIT quotients in full generality. The goal is to explain how the ideas of Ciocan-Fontanine, Kim, and Zhou can be applied in three different settings: configuration spaces of points, maps to GIT quotients, and Hurwitz theory. Based on these examples, I will try to formulate some general principles underlying such wall-crossing phenomena. The final goal is to combine all three settings to provide a wall-crossing between spaces of maps and Hilbert schemes associated to threefolds of the form Surface × Curve.
Wall-crossing in Gromov–Witten theory Iread_more
HG G 43
9 October 2026
16:00-17:30 		Daniel Holmes
IST Austria
Details

Algebraic Geometry and Moduli Seminar

Title Denominators of Hodge integrals
Speaker, Affiliation Daniel Holmes, IST Austria
Date, Time 9 October 2026, 16:00-17:30
Location HG G 43
Abstract will present upcoming work relating the least common denominator of all genus g Hodge integrals to Minkowski numbers, also known as Bhargava factorials associated to the set of primes. As a corollary, we prove a conjecture of Liu-Xu and generalize their result on the orders of automorphism groups of compact Riemann surfaces to stable curves. A fruitful part in this project was played by IMProofBench.
Denominators of Hodge integralsread_more
HG G 43
14 October 2026
13:30-15:00 		Dr. Denis Nesterov
ETH Zürich
Details

Algebraic Geometry and Moduli Seminar

Title Wall-crossing in Gromov–Witten theory II
Speaker, Affiliation Dr. Denis Nesterov, ETH Zürich
Date, Time 14 October 2026, 13:30-15:00
Location HG G 43
Abstract Moduli spaces often admit several natural compactifications. The comparison of different compactifications is referred to as wall-crossing. Some compactifications are simpler than others, making wall-crossing one of the most powerful established techniques, for example, in the study of moduli spaces of sheaves. I will discuss wall-crossing phenomena for moduli spaces of maps (Gromov–Witten theory) and other related spaces. The first glimpses of wall-crossing in Gromov–Witten theory go back to its beginnings, namely to Givental’s proof of mirror symmetry for the quintic in 1990s. Later, independently of Givental’s work, Manin and Bayer were the first to explore the idea of wall-crossing in the setting of maps, extending Hassett’s ideas on weighted marked curves. Only with the work of Ciocan-Fontanine, Kim, and Maulik from 2010s, which in turn builds on the work of many others, did it become possible to exploit different compactifications of moduli spaces of maps with considerable flexibility for GIT quotients, thereby revealing Givental’s proof as a wall-crossing calculation. Zhou then made the next major step by proving the Ciocan-Fontanine–Kim wall-crossing formulas for GIT quotients in full generality. The goal is to explain how the ideas of Ciocan-Fontanine, Kim, and Zhou can be applied in three different settings: configuration spaces of points, maps to GIT quotients, and Hurwitz theory. Based on these examples, I will try to formulate some general principles underlying such wall-crossing phenomena. The final goal is to combine all three settings to provide a wall-crossing between spaces of maps and Hilbert schemes associated to threefolds of the form Surface × Curve.
Wall-crossing in Gromov–Witten theory IIread_more
HG G 43
16 October 2026
16:00-17:30 		Dr. Roberto Fringuelli
University of Pisa
Details

Algebraic Geometry and Moduli Seminar

Title Compactifications of the universal moduli space of vector bundles on stable curves
Speaker, Affiliation Dr. Roberto Fringuelli, University of Pisa
Date, Time 16 October 2026, 16:00-17:30
Location HG G 43
Abstract The universal moduli space of slope-semistable (with respect to the canonical polarization) vector bundles on stable curves is not compact. There are two natural ways to compactify it. The first is to add slope-semistable torsion-free sheaves, while the second is to consider vector bundles on semistable curves. In this talk, we briefly review the compactification by torsion-free sheaves and then focus on the second approach, discussing its main properties and its relationship with the former.
Compactifications of the universal moduli space of vector bundles on stable curvesread_more
HG G 43
21 October 2026
13:30-15:00 		Dr. Denis Nesterov
ETH Zürich
Details

Algebraic Geometry and Moduli Seminar

Title Wall-crossing in Gromov–Witten theory III
Speaker, Affiliation Dr. Denis Nesterov, ETH Zürich
Date, Time 21 October 2026, 13:30-15:00
Location HG G 43
Abstract Moduli spaces often admit several natural compactifications. The comparison of different compactifications is referred to as wall-crossing. Some compactifications are simpler than others, making wall-crossing one of the most powerful established techniques, for example, in the study of moduli spaces of sheaves. I will discuss wall-crossing phenomena for moduli spaces of maps (Gromov–Witten theory) and other related spaces. The first glimpses of wall-crossing in Gromov–Witten theory go back to its beginnings, namely to Givental’s proof of mirror symmetry for the quintic in 1990s. Later, independently of Givental’s work, Manin and Bayer were the first to explore the idea of wall-crossing in the setting of maps, extending Hassett’s ideas on weighted marked curves. Only with the work of Ciocan-Fontanine, Kim, and Maulik from 2010s, which in turn builds on the work of many others, did it become possible to exploit different compactifications of moduli spaces of maps with considerable flexibility for GIT quotients, thereby revealing Givental’s proof as a wall-crossing calculation. Zhou then made the next major step by proving the Ciocan-Fontanine–Kim wall-crossing formulas for GIT quotients in full generality. The goal is to explain how the ideas of Ciocan-Fontanine, Kim, and Zhou can be applied in three different settings: configuration spaces of points, maps to GIT quotients, and Hurwitz theory. Based on these examples, I will try to formulate some general principles underlying such wall-crossing phenomena. The final goal is to combine all three settings to provide a wall-crossing between spaces of maps and Hilbert schemes associated to threefolds of the form Surface × Curve.
Wall-crossing in Gromov–Witten theory IIIread_more
HG G 43
23 October 2026
16:00-17:30 		Dr. Sergej Monavari
University of Padua
Details

Algebraic Geometry and Moduli Seminar

Title The refined local Donaldson-Thomas theory of curves 
Speaker, Affiliation Dr. Sergej Monavari, University of Padua
Date, Time 23 October 2026, 16:00-17:30
Location HG G 43
Abstract The Maulik-Nekrasov-Okounkov-Pandharipande correspondence predicts an equivalence between the partition functions of (numerical) Gromov-Witten and Donaldson-Thomas invariants of smooth projective threefolds. It was recently proposed by Pardon a solution of this conjectural correspondence by reducing to the simpler case of local curves, which are more amenable for computations by means of TQFT methods. Even more recently, inspired by the seminal work of Nekrasov-Okounkov on the index in M-theory, Brini-Schuler proposed a refined GW/DT correspondence. In this talk, I will present a full solution for the Donaldson-Thomas side of the refined GW/DT correspondence in the case of local curves. In particular, I will explain how to derive the refined DT partition function without relying on degeneration techniques, relative invariants and TQFT methods, and how our formulas recover string-theoretic prediction of Aganagic-Schaeffer.
The refined local Donaldson-Thomas theory of curves read_more
HG G 43
28 October 2026
13:30-15:00 		Dr. Claudia Stadlmayr
Université de Neuchâtel
Details

Algebraic Geometry and Moduli Seminar

Title Title T.B.A.
Speaker, Affiliation Dr. Claudia Stadlmayr, Université de Neuchâtel
Date, Time 28 October 2026, 13:30-15:00
Location HG G 43
Title T.B.A.
HG G 43
4 November 2026
13:30-15:00 		Dr. Denis Nesterov
ETH Zürich
Details

Algebraic Geometry and Moduli Seminar

Title Wall-crossing in Gromov–Witten theory IV
Speaker, Affiliation Dr. Denis Nesterov, ETH Zürich
Date, Time 4 November 2026, 13:30-15:00
Location HG G 43
Abstract Moduli spaces often admit several natural compactifications. The comparison of different compactifications is referred to as wall-crossing. Some compactifications are simpler than others, making wall-crossing one of the most powerful established techniques, for example, in the study of moduli spaces of sheaves. I will discuss wall-crossing phenomena for moduli spaces of maps (Gromov–Witten theory) and other related spaces. The first glimpses of wall-crossing in Gromov–Witten theory go back to its beginnings, namely to Givental’s proof of mirror symmetry for the quintic in 1990s. Later, independently of Givental’s work, Manin and Bayer were the first to explore the idea of wall-crossing in the setting of maps, extending Hassett’s ideas on weighted marked curves. Only with the work of Ciocan-Fontanine, Kim, and Maulik from 2010s, which in turn builds on the work of many others, did it become possible to exploit different compactifications of moduli spaces of maps with considerable flexibility for GIT quotients, thereby revealing Givental’s proof as a wall-crossing calculation. Zhou then made the next major step by proving the Ciocan-Fontanine–Kim wall-crossing formulas for GIT quotients in full generality. The goal is to explain how the ideas of Ciocan-Fontanine, Kim, and Zhou can be applied in three different settings: configuration spaces of points, maps to GIT quotients, and Hurwitz theory. Based on these examples, I will try to formulate some general principles underlying such wall-crossing phenomena. The final goal is to combine all three settings to provide a wall-crossing between spaces of maps and Hilbert schemes associated to threefolds of the form Surface × Curve.
Wall-crossing in Gromov–Witten theory IVread_more
HG G 43
25 November 2026
13:30-15:00 		Dr. Sam DeHority
Yale University
Details

Algebraic Geometry and Moduli Seminar

Title Title T.B.A.
Speaker, Affiliation Dr. Sam DeHority, Yale University
Date, Time 25 November 2026, 13:30-15:00
Location HG G 43
Title T.B.A.
HG G 43
27 November 2026
16:00-17:30 		Prof. Dr. Hsian-Hua Tseng
Ohio State University
Details

Algebraic Geometry and Moduli Seminar

Title Title T.B.A.
Speaker, Affiliation Prof. Dr. Hsian-Hua Tseng, Ohio State University
Date, Time 27 November 2026, 16:00-17:30
Location HG G 43
Title T.B.A.
HG G 43
4 December 2026
16:00-17:30 		Prof. Dr. Tudor Pădurariu
University of Bonn
Details

Algebraic Geometry and Moduli Seminar

Title Title T.B.A.
Speaker, Affiliation Prof. Dr. Tudor Pădurariu, University of Bonn
Date, Time 4 December 2026, 16:00-17:30
Location HG G 43
Title T.B.A.
HG G 43

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