**Calf Seminar**

About the Calf

About the Calf

Calf is the junior COW, an algebraic geometry seminar group primarily aimed at PhD students.

The organisers for academic year 2024/25 are Pascal Josiah (Nottingham), Siao Chi Mok (Cambridge), and Alexander Fruh (Birmingham), as well as an extensive network of local organisers at different universities. Calf announcements are made using the COW mailing list. If you would like to get involved in the organisation, or suggest your institution as the next venue, please contact any of the people named above.

The COW seminar has some funding for travel expenses, and information on reimbursement can be found on the main COW webpage.

**Upcoming Meeting:**

University of Bath 16th May 2024

Room TBC

University of Bath 16th May 2024

Room TBC

**Speakers:**

Yannik Schuler (University of Sheffield)

Rhiannon Savage (University of Oxford)

Oliver Daisey (University of Durham)

Yannik Schuler (University of Sheffield)

Rhiannon Savage (University of Oxford)

Oliver Daisey (University of Durham)

**Recent Meeting:**

**University of Birmingham 22nd February 2024**

**Lecture Theatre A, Watson Building 13:00-17:00**

**13:00: Antoine Pinardin (University of Edinburgh)**

Title:G-Solid Rational Surfaces

Title:

**Abstract:**A rational surface is a surface S such that there exists a birational map between S and the projective plane. Given a rational surface S and a finite subgroup G of Aut(S), we are interested in determining whether or not there exists a G-equivariant birational map between S and a G-conic bundle. If not, we say that S is G-solid. The Minimal Model Program for surfaces implies that it is enough to consider the case where S is a smooth Del Pezzo surface. After introducing this formalism, we will present the full classification of pairs (G,S) such that the surface S is G-solid. This classification is motivated by the long lasting problem of classifying the conjugacy classes of finite subgroups of the group of birational self maps of the projective space in dimension 2 and 3.

**14:30: Girtrude Hamm (University of Nottingham)**

**Title:**Combinatorial Automorphisms of Spherical Varieties

**Abstract:**Toric varieties are a special class of variety which can be described by lattice fans and toric morphisms have a neat combinatorial description in terms of lattice homomorphisms. This can be used in classifications to show when the toric varieties of two fans are equivalent. Spherical varieties are a generalisation of toric varieties with a similar combinatorial description, but the description of toric morphisms does not easily generalise to the spherical case. I will give a sketch of how to combinatorially describe spherical varieties and give examples where the expected notion of morphism breaks down. I will then give certain lattice automorphisms which are associated to automorphisms of spherical varieties and which are enough to make some classification questions possible.

**16:00: Alberto Cobos-Rabano (University of Sheffield)**

**Title:**Two Ways of Counting Curves on Toric Varieties

**Abstract:**Gromov-Witten theory and quasimap theory are two approaches towards counting curves on a toric variety. I will give an overview of enumerative geometry and toric geometry in order to introduce the main players: stable maps and stable quasi-maps. We will conclude with some new ideas to compare Gromov-Witten and quasi-map invariants.