**Algebraic Geometry and Mathematical Physics Seminar**, moved to Tuesday at 14:00 UK time;**Pure maths Colloquium**, on Wednesday at 14:00, in J11;**Learning seminar on DT theory**, on Friday at 14:00.

The topology and the cosmology-relativity-gravitation seminars may also be of interest, as well as the complete lists of seminars hosted at the School of Mathematics and Statistics this week and this semester.

Previous seminars of our group are collected here.

- GLEN meeting on Singularities and Derived Categories, November 13-14th, 2019
- BPS states, mirror symmetry, and exact WKB conference, July, 6-10th, 2020.

Tropical multiplicities from polyvector fields and QFT

ZOOM Meeting ID: 762 8025 8504, ask for pw

*Abstract: *When considering planar tropical curves satisfying point conditions, Mikhalkin expressed the tropical curves' multiplicities as the product of the multiplicities of their vertices. Such a...Read more

Prelog Chow rings and stable irrationality in semistable degenerations

*Abstract: *Stably rational varieties admit decompositions of the diagonal following Colliot-Thélène. This criterion for stable irrationality was made applicable in (usually fairly mild)
degenerations by work of Voisin and others....Read more

Quantum differential equations and helices.

*Abstract: *Quantum differential equations (qDEs) are a rich object attached to complex smooth projective varieties. They encode information on their enumerative geometry, topology and (conjecturally) on their algebraic geometry...Read more

Categorification of 2d cohomological Hall algebras

*Abstract:* Let M denote the moduli stack of either coherent sheaves on a smooth projective surface or Higgs sheaves on a smooth projective...
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Partitions and Hilbert schemes of points

*Abstract:* This will be a gentle, expository talk explaining some connections between the two objects in the title. I will begin with...
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A Mayer-Vietoris theorem for Gromov-Witten theory

*Abstract:* The Gromov-Witten theory of a smooth variety X is a collection of invariants, extracted from the topology of the space of ...
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The Stability Manifold of a Contraction Algebra

*Abstract:* For a finite dimensional algebra, Bridgeland stability conditions can be viewed as a continuous generalisation of tilting theory, providing...
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Quasimodular forms from Betti numbers

*Abstract:* I will explain how to construct quasimodular forms starting from Betti numbers of moduli spaces of dimension 1 coherent sheaves on P2. This gives a proof of some stringy predictions about the refined topological string theory of local P2 in the Nekrasov-Shatashvili limit. Partly based on work in progress with Honglu Fan, Shuai Guo, and Longting Wu.

The Gamma and SYZ conjectures: a tropical approach to periods

*Abstract:* I'll start by explaining a new method of computing asymptotics of period integrals using tropical geometry, via some...
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K-theoretic Donaldson-Thomas theory and the Hilbert scheme of points on a surface

*Abstract:* Tautological bundles on Hilbert schemes of points often enter into enumerative and physical computations. I'll explain how to use the Donaldson-Thomas theory of ...
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Strong positivity for quantum cluster algebras

*Abstract:* I will discuss the positivity for quantum theta functions, a result of joint work with Travis Mandel. For...
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Stability conditions on the derived category of coherent systems and Brill-Noether theory

*Abstract:* A classical method to study Brill-Noether locus of higher rank semistable vector bundles on curves is to examine the stability of coherent systems. To have an abelian category we enlarge the...
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Non-archimedean and motivic integrals on the Hitchin fibration

*Abstract:* Based on mirror symmetry considerations, Hausel and Thaddeus conjectured an equality between ‘stringy’ Hodge numbers for...
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Higher SL(k)-friezes

*Abstract:* Classical frieze patterns are combinatorial structures which relate back to Gauss’ Pentagramma Mirificum, and have been extensively studied by Conway and Coxeter in the 1970’s....
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Intersection theory of derived stacks

*Abstract:* I will discuss how various formalisms of intersection theory (Chow groups, K-theory, cobordism) can be extended to the setting of derived schemes and stacks. This gives a new approach to virtual phenomena such as the virtual fundamental class and virtual Riemann-Roch formulas.

Generalization of the Givental theory for the open WDVV equations

*Abstract:* The WDVV equations, also called the associativity equations, is a system of non-linear partial differential equations for one function that describes the local structure of a Frobenius manifold. In enumerative geometry the WDVV equations...
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Smoothing toroidal crossing varieties

*Abstract*: Friedman and Kawamata-Namikawa studied smoothability of normal crossing varieties. I present the proof of a significantly...Read more

Quantum modularity

*Abstract: *Lawrence and Zagier have shown that for a Brieskorn homology sphere there exists a power series with...Read more

Algebraic Geometry seminars: 2018/19, 2017/18, 2016/17, 2014-16

Learning seminars

- semester 1: K3 surfaces
- 2018/19: Toric Varieties
- 2017/18: Stacks; and Singularity Category of ADE Singularities
- 2016/17: Topics in Derived Categories; and Singularity Category, MCM modules and Matrix Factorization