There are no events at the Simons Center today. Here are the events for this week

Monday, January 23rd, 2023

Hyperkahler Program Seminar: Claudio Onorati

Time: 10:30 AM - 12:30 PM

Location: SCGP 313

**Title:**Some remarks on deformations of hyperholomorphic bundles**Abstract:**in this talk I will recall the definition and main properties of hyperholomorphic bundles on hyperkahler varieties, and I will explain two results obtained jointly with F. Meazzini about the infinitesimal deformations of such objects. The first result states that the differential graded Lie algebra controlling the deformations of such a bundle is formal, i.e. quasi-isomorphic to its cohomology. The second result focuses on the space of hyperholomorphic connections and gives an explicit differential graded Lie algebra controlling the deformation functor of such connections.
Tuesday, January 24th, 2023

Hyperkahler Program Seminar: Arvid Perego

Time: 10:30 AM - 12:30 PM

Location: SCGP 313

**Title:**Irreducible symplectic varieties from moduli spaces of sheaves**Abstract:**Moduli spaces of semistable sheaves over projective K3 surfaces form a wide family of examples of irreducible symplectic varieties. We will present a proof of this, and we will give a description of their second integral cohomology. This is a joint work with A. Rapagnetta.
Wednesday, January 25th, 2023

Hyperkahler Program Seminar: Giovanni Mongardi

Time: 10:30 AM - 12:30 PM

Location:

**Title:**Wall divisors and birational geometry of primitive symplectic varieties**Abstract:**In this talk, we will introduce an extension of the notion of wall divisors (a.k.a. MBM classes) to the singular setting, and we will discuss how they can be used to determine birational models of PSVs. This is part of a joint work with Ch. Lehn and G. Pacienza
Thursday, January 26th, 2023

**Math Event:**Symplectic Geometry, Gauge Theory, and Low-Dimensional Topology Seminar: Ian Montague - Seiberg-Witten Floer K-Theory and Cyclic Group Actions

Time: 1:00 PM - 2:30 PM

Location: Math Tower 4-130

**Title:**Seiberg-Witten Floer K-Theory and Cyclic Group Actions**Speaker:**Ian Montague [Brandeis]**Abstract:**Given a spin rational homology sphere equipped with a cyclic group action preserving the spin structure, I will introduce equivariant refinements of Manolescu's kappa invariant, derived from the equivariant K-theory of the Seiberg--Witten Floer spectrum. These invariants give rise to equivariant relative 10/8-ths type inequalities for equivariant spin cobordisms between rational homology spheres. I will explain how these inequalities provide applications to knot concordance, obstruct cyclic group actions on spin fillings, and give genus bounds for knots in punctured 4-manifolds. If time permits I will explain how these invariants are related to equivariant eta-invariants of the Dirac operator, and describe work-in-progress which provides explicit formulas for the S^1-equivariant eta-invariants on Seifert-fibered spaces. View Details