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Topological recursion for Masur–Veech volumes

J. E. Andersen, G. Borot, S. Charbonnier, V. Delecroix, D. Lewański, C. Wheeler J. London Math. Soc. 107.1 2023 arXiv DOI
Abstract

We study the Masur–Veech volumes of quadratic differentials, showing they correspond to constant terms of polynomials determined by topological recursion/Virasoro constraints.

A new spin on Hurwitz theory and ELSV via theta characteristics

R. Kramer, D. Lewański Accepted in in Selecta Math. 2025 arXiv
Abstract

We study spin Hurwitz numbers, which count ramified covers of the Riemann sphere with a sign coming from a theta characteristic. We conjecture a topological recursion governing these counts, and prove equivalence with an ELSV formula.

teaching

Riemann Surfaces

Undergraduate course, ETHZ, Spring 2024

A first introduction to the theory of Riemann surfaces. These are beautiful objects that sit at the intersection of algebra, geometry, and analysis. We covered the theorems of Riemann–Hurwitz, Riemann–Roch, and Abeli–Jacobi, as well as the basics of Hurwitz theory.

Toric Geometry

Undergraduate course, ETHZ, Spring 2025

Toric varieties provide a rich class of examples in algebraic geometry that bridge combinatorics and geometry, making them an ideal starting point for exploring the interplay between these fields. We will introduce toric varieties, study their combinatorial and abstract structures, and examine their basic geometry, including Picard groups, cohomology, and singularities.