Informal seminar on combinatorics and representation theory

This is an informal seminar on combinatorics and representation theory.
In Winter 2021 discussed the combinatorics of q,t-Catalan numbers and Shuffle conjecture,
as well as their geometric counterparts: affine Springer fibers and positroid varieties.
In Spring 2021 we will discuss combinatorics related to affine Schubert calculus.
Organizers: Erik Carlsson , Eugene Gorsky, Anne Schilling, Monica Vazirani .
The seminar meets on Mondays at 11am.
Notes from past quarters: Fall 2020 .


1/4 Organizational meeting. Notes

1/11 Erik: A combinatorial formula for the nabla operator

1/18 MLK Day

1/25 Erik continues

2/1 Erik continues

2/8 Joseph (recap from last quarter ) notes

2/15 Presidents Day

2/22 Joseph continues notes

3/1 Eugene: sections 2-3 of [KLS] notes

3/8 Eugene: sections 4-5 of [KLS] notes

3/15, 3/22: Spring break

3/29 Eugene: section 7 of [KLS] notes

4/5 Anne: intro to affine Schubert calculus notes

4/12 Jianping on notes

4/19 Jianping continued notes

4/26 Yue Zhao notes

5/3 Emi Brawley notes , Josh Petrack notes

5/10 Milo Bechtloff Weising


  1. [CM] E. Carlsson, A. Mellit. A combinatorial formula for the nabla operator. arXiv:2012.01627
  2. [KLS] A. Knutson, T. Lam, D. Speyer. Positroid Varieties: Juggling and Geometry. arXiv:1111.3660
  3. [GL] P. Galashin, T. Lam. Positroids, knots, and q,t-Catalan numbers.arXiv:2012.09745