Online seminar · 2022–2023
Real Reductive Groups/Atlas of Lie Groups and Representations Seminar
A working/learning seminar on Zoom, on Thursdays, 10:30 AM – noon (EST), beginning January 6, 2022.
The seminar has concluded. Thank you for your attendance! Recordings, slides and notes of the talks are listed below.
About the seminar
This was a working/learning seminar on (infinite-dimensional) representations of real reductive groups, aimed at grad students and researchers having some familiarity with representations of compact Lie groups. It used the atlas software; participants installed it on their laptops following the directions on the software page.
The aim was for each seminar to last approximately one hour; the extra half hour in the schedule was meant to encourage lots of interaction with the audience. The idea of the seminar is that learning how the software does mathematical computations is an excellent way to understand the mathematics, as well as a great source of examples.
First goal is to learn how the software represents real reductive groups (precisely, the group of real points of any complex connected reductive algebraic group) and their representations; making sense of the software will lead to an understanding of the underlying mathematics. Second goal is to use the software to investigate experimentally questions about reductive groups.
A good general introduction to what the seminar is about can be found at www.liegroups.org/workshop2017/workshop/videos_and_computer from a 2017 workshop. The mathematical subject matter is described in the slides www.liegroups.org/workshop2017/workshop/presentations/voganHO.pdf from Vogan’s lecture. The main ideas about how to realize this mathematics on a computer are described in Adams’s lecture www.liegroups.org/workshop2017/workshop/presentations/adams1HO.pdf. A quick introduction to the syntax for the software is in van Leeuwen’s presentation www.liegroups.org/workshop2017/workshop/computer_transcripts/vanLeeuwen1.out.
The home page for the seminar is on the Research Seminars web site: Research Seminars/Atlas. There you’ll find an introduction to the seminar, suggested background reading and a schedule of talks.
When the seminar concluded, it was to continue, based on demand, as an Atlas Help Session, answering questions about the software and the mathematics behind it. There is a Slack workspace for questions and discussions about all aspects of the atlas software: join the workspace.
Recordings and slides
Talks are listed in reverse chronological order. The recordings are on MIT Zoom. The links to the slides for individual talks may require you to be logged in to a Microsoft account; if that’s an issue, use the notebook of all the slides and open the slides for individual talks from there.
2023
| Date | Speaker | Title | Recording and slides |
|---|---|---|---|
| February 2, 2023 | Jeffrey Adams | Some examples | No video Slides Terminal IO |
| January 26, 2023 | David Vogan | Computing Unitary Duals III: unitary_dual@RealForm | Video Slides |
| January 19, 2023 | David Vogan | Computing Unitary Duals II: non-unitary certificates | Video Slides |
| January 12, 2023 | David Vogan | Computing Unitary Duals I: cohomological induction | Video Slides |
2022
| Date | Speaker | Title | Recording and slides |
|---|---|---|---|
| December 15, 2022 | Adams/Vogan | Interesting examples of Arthur packets, computed by Annegret's script | Video Slides |
| December 8, 2022 | David Vogan | More on honest Arthur packets/Annegret Paul's magic scripts | Video Slides |
| December 1, 2022 | David Vogan | More on honest Arthur packets/Annegret Paul's magic scripts | Video Slides |
| November 17, 2022 | Jeffrey Adams/David Vogan | Arthur Packets for G2 /Induction for Arthur packets | Video Slides |
| November 10, 2022 | Jeffrey Adams | Arthur Packets for G2 | Video Slides |
| November 3, 2022 | Jeffrey Adams | Examples of Duality/Miscellaneous 2 | Video Slides |
| October 27, 2022 | Jeffrey Adams | Examples of Duality/Miscellaneous | Video Slides |
| October 20, 2022 | David Vogan | Duality, associated varieties, and nilpotent orbits 3 | Video Slides |
| October 13, 2022 | David Vogan | Duality, associated varieties, and nilpotent orbits 2 | Video Slides |
| September 29, 2022 | David Vogan | Duality, associated varieties, and nilpotent orbits | Video Slides |
| September 22, 2022 | Jeffrey Adams | Cohomological Arthur packets 3 | Video Slides |
| September 15, 2022 | Jeffrey Adams | Cohomological Arthur packets 2 | Video Slides |
| September 8, 2022 | Jeffrey Adams | Cohomological Arthur packets | Video Slides |
| September 1, 2022 | David Vogan | More about discrete series restriction | Video Slides |
| August 25, 2022 | David Vogan | Cohomological induction and restricting discrete series to K | Video Slides |
| August 18, 2022 | Jeffrey Adams | Hermitian forms on finite dimensional representations | Video Slides |
| August 11, 2022 | David Vogan | More on duality for singular and non-integral infinitesimal character | Video Slides |
| August 4, 2022 | David Vogan | Duality for singular and non-integral infinitesimal character | Video Slides |
| July 28, 2022 | Jeffrey Adams | Vogan duality and Arthur Packets | Video Slides |
| July 21, 2022 | Jeffrey Adams | Vogan duality | Video Slides |
| July 7, 2022 | David Vogan | Affine Weyl group, facets, and the unitary dual | Video Slides |
| June 30, 2022 | David Vogan | Classifying the unitary dual (part 1 of infinitely many…) | Video Slides |
| June 23, 2022 | David Vogan | Dirac Operator in Atlas | Video Slides |
| June 9, 2022 | Jeffrey Adams | Loose ends, Jantzen filtration, Questions from the audience | Video Slides |
| June 2, 2022 | Jeffrey Adams | Loose ends: More on translation, some answers to questions | Video Slides |
| May 26, 2022 | Jeffrey Adams | Loose ends: Hermitian representations, translation, the Jantzen filtration | Video Slides |
| May 19, 2022 | David Vogan | Unitary Dual of F4_B4 in atlas | Video Slides |
| May 12, 2022 | David Vogan | Unitary Dual of SO(2n,1) in atlas | Video Slides |
| May 5, 2022 | Jeffrey Adams | Theta-stable parabolic subgroups and cohomological induction in atlas | Video Slides |
| April 28, 2022 | David Vogan | Real parabolic subgroups and induction in atlas | Video Slides |
| April 21, 2022 | Jeffrey Adams | Unipotent Representations, Nilpotent Orbits and the Weyl group II | Video Slides |
| April 14, 2022 | Jeffrey Adams | Unipotent Representations, Nilpotent Orbits and the Weyl group I | Video Slides |
| April 7, 2022 | David Vogan | Nilpotent orbits and atlas | Video Slides |
| March 31, 2022 | David Vogan | Gelfand-Kirillov dimension and atlas | Video Slides |
| March 24, 2022 | Jeffrey Adams | Weyl group representations in Atlas II | Video Slides |
| March 17, 2022 | Jeffrey Adams | Weyl group representations in Atlas I | Video Slides |
| March 10, 2022 | David Vogan | How atlas does what it says its doing | Video Slides |
| March 3, 2022 | Jeffrey Adams | Signature character formulas and unitary representations 2SL2 refcard from the talk File unavailable | Video Slides |
| February 24, 2022 | Jeffrey Adams | Signature character formulas and unitary representations(or why we needed this software in the first place) | Video Slides |
| February 17, 2022 | David Vogan | Character formulas and Kazhdan-Lusztig polynomials(or why we needed this software in the first place) | Video Slides |
| February 10, 2022 | Jeffrey Adams | The Atlas Way (More on KGB) | Video Slides |
| February 3, 2022 | David Vogan | Understanding K: How Atlas understands compact subgroups | Video Slides |
| January 27, 2022 | Jeffrey Adams | Branching to K | Video Slides |
| January 20, 2022 | David Vogan | Parameters for Representations | Video Slides |
| January 13, 2022 | Jeffrey Adams | Root Data/Complex and Real reductive groups | Video Slides |
| January 6, 2022 | David Vogan | What Groups/Representations/Software? | Video Slides |