# George H. Seelinger

I am a mathematics researcher working in algebraic combinatorics while keeping open arms towards representation theory and algebraic geometry. Currently, I am a Postdoctoral Assistant Professor at the Univeristy of Michigan; I received my PhD in Mathematics at the University of Virginia working under Dr. Jennifer Morse. Previously, I worked as a Data Scientist on real time bidding problems for an internet advertising company. Generally, I am interested in working on unsolved problems and enabling other problem solvers to be more effective.

## Contact

Email: ghseeli@umich.edu

My Pronouns: He/Him/His

Think we have met before? Here is my professional past and present travel schedule.

## Research and Writings • (Papers and Talks) • (CV)

I am interested in problems involving algebraic combinatorics. Recently, I have been working on problems in the following areas.

- Schubert calculus (and its generalizations): finding symmetric function representatives for Schubert classes in order to prove new results.
- Macdonald polynomials and positivity questions: finding new ways to examine symmetric functions related to Macdonald polynomials and understand why they expand positively into certain distinguished bases.
- Catalan functions: finding new applications to existing open problems involving symmetric functions.

Also, as a resource for my cohort of graduate students, but also for other learning graduate students, I worked with various collaborators on creating class notes for first and some second year PhD program courses. You can see them here: First year course notes.

I also publicly post monographs I write for myself to clarify concepts and fill in details of books I read. You can see them here: Monographs; I also have made select notes for more advanced classes I have taken, but they are more likely to have errors and some are incomplete: Advanced course notes.

## Teaching • (All)

I am teaching Matrix Algebra (Math 417) during the Winter 2022 semester.

## Engagement, Outreach, and Service

I sometimes make contributions to the open source mathematical software SageMath, including overhauling the diagram algebras package with my collaborators as a result of my work on Brauer algebras and implementing Young's raising operators with my collaborators on projects involving Catalan functions. You can see all the tickets I have contributed to the SageMath trac server. If you are interested in contributing code to Sage, check out my development checklist and feel free to contact me if you have questions!

I am co-organizing a learning seminar in algebraic combinatorics at UM.

In graduate school, I was a member of and webmaster for the UVA Association for Women in Mathematics (AWM). AWM works to encourage girls and women to study and have activer careers in the mathematical sciences and promote equal opportunity and equal treatment of girls and women in the mathematical sciences.

Previously, I volunteered as a UVA Math Ambassador to do math outreach in Charlottesville area grade schools.

Previously, I have been a mentor for the UVA Math Department Directed Reading Program (DRP). The DRP pairs undergraduates interested in learning math outside the standard curriculum with graduate student mentors who guide them in reading some interesting and different mathematics. For instance, I mentored a student about the theoretical foundations of machine learning, culminating in understanding the SVM classification algorithm and the theoretical justification for SVM as a classifier.

## What's New

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Abstract: The Shuffle Theorem, conjectured by Haglund, Haiman, Loehr, Remmel and Ulyanov, and proved by Carlsson and Mellit, describes the characteristic of the $S_n$-module of diagonal harmonics as a weight generating function over labeled Dyck paths under a line with slope −1. The Shuffle Theorem has been generalized in many different directions, producing a number of theorems and conjectures. We provide a generalized shuffle theorem for paths under any line with negative slope using different methods from previous proofs of the Shuffle Theorem. In particular, our proof relies on showing a “stable” shuffle theorem in the ring of virtual GL_l-characters. Furthermore, we use our techniques to prove the Extended Delta Conjecture, yet another generalization of the original Shuffle Conjecture.

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During these unprecedented times, I have seen a number of creative alternatives to in person talks. One of these solutions is the Junior Mathematian Research Archive. Essentially, early career researchers can propose to submit a video about a paper they have recently submitted to arXiv. So, I figured I would give it a shot and gave a short talk about part of my paper with Jonah Blasiak and Jennifer Morse on \(K\)-theoretic Catalan functions.

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This past semester (Fall 2019), I taught “flipped calculus” for the first time at UVA. It was a whirlwind experience with many challenging but also rewarding aspects. As one professor told me “I do not want to hear your abstract teaching philosophy” and so I wish to clarify that this write-up is merely a reflection on my experiences and lessons learned while teaching this new classroom model; it is not meant to be didactic.

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This past week I had the opportunity to give my first public research presentation as a graduate student at Adriano Garsia’s 90th birthday conference, Garsiafest, in San Diego at the Scripps Seaside Forum. My presentation mainly expanded on the information from my MAAGC Poster, but now one of the main conjectures is a theorem! You can look at the slides here. Eventually, they will also post a video of my talk on the conference website. It was truly an honor to present my work to so many people in my area and I look forward to presenting more work in the future.

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This past week, I was lucky enough to meet and attend some lectures given by Ole Warnaar at the Virginia Integrable Probability Summer School 2019 on Schur Functions and Schur Processes since I was not traveling. As someone who does research in symmetric function theory, I had already seen much of what Dr. Warnaar presented in his lecture series (which is all recorded and posted online at the linked course page), but I used the opportunity to make some significant additions to my notes on plethystic substitution. In particular, I had never seen an introductory lecture on plethystic substitution for symmetric functions despite using and seeing it in research papers, and so it was a great opportunity to learn something new at a basic level. Furthermore, his approach was different to what I had seen in Macdonald’s book, so it was great to get a different persepctive on it all. I was also curious to learn more about Schur processes since I do not think about probability for my research at the moment, but unfortunately there was not enough time to get too deep into the subject. I hope I will have a chance to learn more about it later, though!

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This last weekend, I had an opportunity to attend and present a poster at the 2019 Mid-Atlantic Algebra, Geometry, and Combinatorics (MAAGC) conference in Philadelphia. The poster is about one of the projects I am currently working on to describe “\(K\)-theoretic \(k\)-Schur functions” with a raising operator formula which is a specialization of what we are currently calling “\(K\)-theoretic Catalan functions” since they generalize the description of Catalan functions that Blasiak, Morse, Pun, and Summers used to prove the Schur positivity of \(k\)-Schur functions.

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