AMS Special Session on Interactions between geometry, combinatorics, and flag varieties

Saint Louis University, Saint Louis, MO

October 18-19, 2025

Description

Flag varieties are important objects of interest in Lie theory, combinatorial algebraic geometry, and representation theory. The study of these varieties is well-established, and the theory describing them yields results that demonstrate a deep connection between geometry, algebra, and combinatorics. The combinatorial aspects of the flag variety enhance our understanding of its geometry and the geometry of its subvarieties, while simultaneously being informed by it.

This session will bring together researchers with interests in both geometric and combinatorial aspects of flag varieties and their subvarieties: Schubert varieties, K-orbit closures, and Hessenberg varieties. Such research frequently involves important combinatorial objects such as symmetric functions, partitions, root systems, and Coxeter groups. This special session will promote collaborations between mathematicians who work in this area of combinatorics and geometry and who are driving current developments in the field.

Session organizers

Information

Confirmed Speakers

Schedule

The registration desk will be located in the Tegeler Hall Lobby. Registration Desk Hours:

Talks for our session will be held in Ritter Hall Room 231, with coffee available in the Ritter Hall Lobby.

Independently of the AMS, the SLU Department of Mathematics and Statistics will host a reception and poster session on Saturday from 5:00 pm - 6:00 pm on Saturday.

Saturday, October 18, 2025 Morning Session

Time Speaker Abstract Slides
8:00 - 8:20 am Ada Stelzer Surprise polynomality and Schubert structure constants
8:30 - 8:50 am Ian Cavey Standard monomial theory and Hilbert schemes Slides
9:00 - 9:20 am Judy Chiang The Prism Tableau Model for Grothendieck Polynomials
9:30 - 9:50 am Adam Daniel Gregory Tableau Formula for Vexillary Double Edelman–Greene Coefficients Slides
10:00 - 10:20 am Cesar Meza Generic torus orbits in matrix Schubert varieties Slides
10:30 - 10:50 am Andrew Hardt Schubert Calculus Stability

Saturday, October 18, 2025 Afternoon Session

Time Speaker Abstract Slides
2:00 - 2:20 pm Sean Griffin Affine Springer fibers and the Shuffle and Delta Theorems Slides
2:30 - 2:50 pm Mee Seong Im Parabolic induction for Springer fibers of type C Slides
3:00 - 3:20 pm Julianna Tymoczko Quantum representations, webs, and Springer fibers
3:30 - 3:50 pm Alexander Yong A Combinatorial Formula for GL-Irreducible Multiplicities of Type A Quiver Loci
4:00 - 4:20 pm Zijing Zhuang On Peterson varieties and generalized Peterson varieties
4:30 - 4:50 pm Edward Richmond Staircase diagrams, pattern avoidance, and smooth Schubert varieties Slides

Sunday, October 19, 2025 Morning Session

Time Speaker Abstract Slides
8:00 - 8:20 am Mahir Bilen Can Levi Bands and Toric Richardson Varieties
8:30 - 8:50 am William Graham Irreducible Characteristic Cycles for Orbit Closures of a Symmetric Subgroup Slides
9:00 - 9:20 am Rachel Wu Smoothing Schubert classes by homogeneous subvarieties Slides
9:30 - 9:50 am Rebecca Goldin On the cohomology rings of some Hessenberg varieties Slides
10:00 - 10:20 am Mark Colarusso Orbits on the product of two flags and a line and the Bruhat order Slides
10:30 - 10:50 am Fernando Diaz Morera Shellability of a Family of Symmetric Spaces Slides

Sunday, October 19, 2025 Afternoon Session

Time Speaker Abstract Slides
2:00 - 2:20 pm Hugh Dennin Cauchy identities for Schubert polynomials and a dual RSK correspondence through pipe dreams
2:30 - 2:50 pm Avery St. Dizier Presenting the Cohomology of a Schubert Variety
3:00 - 3:20 pm Reuven Hodges Orbit Structures and Complexity in Schubert Varieties and Richardson Varieties Slides
3:30 - 3:50 pm Nathan Lesnevich The Second Cohomology of Hess(S,H) and the Dot Action in types B/C Slides
4:00 - 4:20 pm Alexander Woo Regular minimal indecomposable Hessenberg Varieties Slides
4:30 - 4:50 pm Cristina Sabando Alvarez Minimal Hessenberg functions for Schubert varieties