This is the homepage of the University of Illinois Urbana-Champaign Algebraic Geometry Seminar, organized by Deniz Genlik and Sheldon Katz. We meet Tuesdays at 3-3:50pm, Loomis Laboratory 136 .
Other algebraic geometry activities at Illinois: AG lunch (Tu 12:30-1:30pm, Harker Hall 201), AG preprint seminar (Tu 2-2:50pm Loomis Laboratory 136). For more information, join our mailing list, either by visiting here or emailing Felix Janda, or Sheldon Katz.
Spring 2026 Schedule:
Sep 1: Orgranizational Meeting at 3:00 pm, Loomis Laboratory 136
Sep 8: Ruoxi Li (University of Illinois Urbana-Champaign
Title: Shifted Logarithmic Functions and More
Abstract: To some extent, a perfect obstruction theory in the sense of Behrend--Fantechi is the shadow of a quasi-smooth derived Deligne--Mumford stack, while a cosection of a perfect obstruction theory in the sense of Kiem-Li is the shadow of a (-1)-shifted function on a quasi-smooth derived Deligne--Mumford stack. In this talk, I will introduce shifted logarithmic functions on derived stacks equipped with log structures of Deligne--Faltings type, and logarithmic cosections of logarithmic perfect obstruction theories. As an application, I will present a decomposition theorem for virtual cycles, after Log GLSM. Meanwhile, I will discuss another facet of shifted logarithmic functions: their derived critical loci carry shifted logarithmic symplectic structures, building on work of Calaque-Safronov. If time permits, I will mention the construction of deformation to log normal bundles.
Sep 15: William Newman (The Ohio State University)
Title: Chow motives of Enriques surfaces
Abstract: An Enriques surface is a 2-dimensional smooth projective variety whose first Betti number is 0 and whose canonical bundle is 2-torsion. There are many such varieties: the moduli space is 10-dimensional. Unlike other famous examples of surfaces with positive dimensional moduli, Enriques surfaces have trivial Hodge structures on their cohomology, so this invariant cannot be used to tell them apart. In this talk, we consider a finer invariant, the integral Chow motive of an Enriques surface, and investigate what information about the Enriques surface it remembers. This is joint work with Jake Huryn.
Sep 22: Deniz Genlik
Title: From 3-spin relations to negative r-spin relations
Abstract: We show negative r-spin relations of Chidambaram--Garcia-Failde--Giacchetto are implied by the Pixton’s 3-spin relations. To achieve this, mainly we extend a result of Janda to generically semi-simple CohFTs with a non-flat unit and perform a detailed asymptotic analysis of shifted Chiodo CohFT under the limit of a parameter. Consequently, we prove that the negative r-spin relations hold in the tautological Chow ring. This is a joint work with Felix Janda.
Sep 29: Lena Ji
Oct 6: TBD
Oct 13: TBD
Oct 15: Hsian-Hua Tseng(The Ohio State University) -- Depatmental Colloquium
Oct 17-Oct 18: Workshop on Topological Recursion and Related Topics
Oct 20: Alessandro Giacchetto (ETH)
Oct 21: Maria Monks Gillespie (Colorado State University)--Combinatorics Colloquium
Oct 27: TBD
Nov 3: TBD
Nov 10: TBD
Nov 17: TBD
Dec 1: TBD
Dec 8: TBD
Events with red color are algebraic geometry related events that are advertised here. They are not part of the seminar.