The IPAC (Important Papers in Algebraic Combinatorics) Seminar Homepage


The 2025 IPAC seminar is co-organized by
Jim Haglund of Penn, and Anna Pun of Baruch College,


Link to the 2021 IPAC webpage
Link to the 2022 IPAC webpage
Link to the 2023 IPAC webpage
Link to the 2024 IPAC webpage

The theme of the seminar is to work through articles/arXiv preprints which represent important current developments, at least initially in algebraic combinatorics. The seminar will meet (via zoom) on Tuesdays and Thursdays from 12-1pm Philadelphia time (unless otherwise noted in the schedule below). Each seminar session will have a "host" who will be responsible for presenting material, but the degree to which the seminar will be a series of lectures or more of a group discussion may vary from week to week. If you wish to attend the talks email me or Anna to get the zoom link (jhaglund "at symbol" math.upenn.edu, annapunying "at symbol" gmail.com). Recordings of the talks will be made if the host is agreeable.

The first two papers we will be working through this summer are "A combinatorial skewing formula for the Rise Delta Theorem" and "A geometric interpretation for the Delta Conjecture", both coauthored by Maria Gillespie, Eugene Gorsky and Sean Griffin (available on the arXiv). The seminar will run from early June to mid August. See the table below for our schedule for the 2025 Summer Season.

The 2025 IPAC Seminar Schedule

Date                   Host                              Paper                              Lecture Recordings                              Lecture Notes                              
6/3, 12 noon Philadelphia time Maria Gillespie (Colorado State) A combinatorial skewing formula for the Rise Delta Thereom (joint with Eugene Gorsky and Sean Griffin) Lecture 1 Notes on Lecture 1
6/5, noon Philadelphia time Maria A combinatorial skewing formula for the Rise Delta Thereom Lecture 2 Notes on Lecture 2
6/10, 12 noon Philadelphia time Maria A combinatorial skewing formula for the Rise Delta Thereom Lecture 3 Notes on Lecture 3
6/12, 12 noon Philadelphia time Sean Griffin (Univ. of Vienna) A geometric interpretation of the Delta Conjecture (joint with Maria Gillespie and Eugene Gorsky) Lecture 1 Notes on Lecture 1
6/17, 12 noon Philadelphia time Sean A geometric interpretation of the Delta Conjecture Lecture 2 Notes on Lecture 2
6/24, 12 noon Philadelphia time Sean A geometric interpretation of the Delta Conjecture Lecture 3 Notes on Lecture 3
6/26, 12 noon Philadelphia time Sean A geometric interpretation of the Delta Conjecture Lecture 4 Notes on Lecture 4
7/3, 11 am Philadelphia time Meesue Yoo (Chungbuk National Univ.) α-chromatic symmetric functions (joint with Jim Haglund and Jaeseong Oh) Lecture 1 Lecture 1 Notes
7/8, 11 am Philadelphia time Jim Haglund (Univ. of Pennsylvania) α-chromatic symmetric functions Lecture 2
7/10, 11 am Philadelphia time Jaeseong Oh (KIAS) α-chromatic symmetric functions Lecture 3
8/5, 10:00am Philadelphia time Tatsuyuki Hikita (RIMS, Kyoto Univ.) A Proof of the Stanley-Stembridge Conjecture Lecture 1
8/7, 10:00am Philadelphia time Tatsuyuki A Proof of the Stanley-Stembridge Conjecture Lecture 2 Lecture 2 Notes
8/12, 10:00am Philadelphia time Tatsuyuki A Proof of the Stanley-Stembridge Conjecture Lecture 3 Lectures 3 and 4 Notes
8/14, 10:00am Philadelphia time Tatsuyuki A Proof of the Stanley-Stembridge Conjecture Lecture 4
8/19, 10:00am Philadelphia time Tatsuyuki A Proof of the Stanley-Stembridge Conjecture Lecture 5
8/21, 10:00am Philadelphia time Tatsuyuki A Proof of the Stanley-Stembridge Conjecture Lecture 6