Research


Here are my preprints, publications, lecture notes, slides, conferences, students, and miscellanea.

The material below is based upon work partially supported by NSF grants DMS-0071606, DMS-0300106, DMS-0554118, DMS-0968275, DMS-0968060, and DMS-1302237, NSA Grant MSFP-06Y-095, and the Simons Foundation.



Preprints:


A note on the orbits of a symmetric subgroup in the flag variety
(with Leticia Barchini), February 2024, preprint, arxiv

Relating real and p-adic Kazhdan-Lusztig polynomials
(with Leticia Barchini), February 2024, preprint, arxiv



Publications:


Unitary representations of real reductive groups
(with Jeffrey Adams, Marc van Leeuwen, and David Vogan) arxiv
Astérisque, volume 417 (2020), 186pp. Sample

Reducible characteristic cycles of Harish Chandra modules for U(p,q) and the Kashiwara-Saito singularity
(with Leticia Barchini and Petr Somberg), arxiv
Communications in Algebra, Volume 47 (2019), no. 12, 4874-4888.

Dirac index and twisted characters
(with Dan Barbasch and Pavle Pandzic) arxiv
Transactions of the AMS, Volume 371 (2019), no. 3, 1701-1733.

Laplacians on Spheres
(with Henrik Schlichtkrull and David Vogan), arxiv
São Paulo Journal of Mathematics, Volume 12 (2018), no. 2, 295-358.

Codimension one connectedness of the graph of associated varieties
(with Kyo Nishiyama and Akihito Wachi) arxiv
Tohuku Journal of Math. (2), Volume 68, Number 2 (2016), 199-239.

The mathematical work of David A. Vogan, Jr.
(with W. M. McGovern) pdf
Representations of Reductive Groups (in Honor of the 60th Birthday of David A. Vogan, Jr.),
Progress in Mathematics, volume 312 Birkhauser/Springer (2016), 1-10.

Algebraic and analytic Dirac induction for graded affine Hecke algebras
(with Dan Ciubotaru and Eric Opdam) arxiv or final pdf
Journal de l'Institute de Mathematiques de Jussieu (JIMJ), 13 (2014), no. 3, 447-486.

Appendix to: Small representations, string instantons, and Fourier modes of Eisenstein series by Michael B. Green, Stephen D. Miller, and Pierre Vanhove
(with Dan Ciubotaru) arxiv
Journal of Number Theory, 146 (2013), 187-309.

Characters of Springer representations on elliptic conjugacy classes
(with Dan Ciubotaru) arxiv or final pdf
Duke Mathematical Journal, 162 (2013), no. 2, 201-223.

Dirac cohomology for graded affine Hecke algebras
(with Dan Barbasch and Dan Ciubotaru) arxiv or final pdf
Acta Mathematica, 209 (2012), no. 2, 197-227.

The exotic Robinson-Schensted correspondence
(with Anthony Henderson) arxiv
Journal of Algebra, 370 (2012), 32-45.

Duality for nonlinear simply laced groups
(with Jeffrey Adams) arxiv or pdf
Compositio Mathematica, 148 (2012), no. 03, 931-965.

Duality for GL(n,R) and the degenerate affine Hecke algebra for gl(n)
(with Dan Ciubotaru) arxiv or pdf
American Journal of Math. 134 (2012), no. 1, 141-170.

Regular orbits of symmetric subgroups on partial flag varieties
(with D. Ciubotaru and K. Nishiyama) arxiv or pdf
Representation Theory, Complex Analysis, and Integral Geometry Vol. 2
Progress in Mathematics, Birkhauser (2012), 61-86.

Stable combinations of special unipotent representations
(with Dan Barbasch) arxiv or pdf
Contemp. Math. 557 (2011), 213-228.

Functors for unitary representations of real classical groups and affine Hecke algebras
(with Dan Ciubotaru) arxiv or pdf
Advances in Math 227 (2011), no. 4, 1585-1611.

Pattern avoidence and smoothness for orbits of a symmetric subgroup in the flag variety
(with W. M. McGovern) arxiv or pdf
Journal of Algebra, 322 (2009), 2713-2730.

Integrals over the Springer fiber for sl(n,C) pdf
a stand-alone version of an appendix which appeared in
Representation Theory, 12 (2008), 403-434.

Leading term cycles of Harish-Chandra modules and partial orders on components of the Springer fiber pdf
Compositio Mathematica, 143 (2007), 515-540.

Some small unipotent representations of indefinite orthogonal groups and the theta correspondence
(with Annegret Paul) pdf
University of Aarhus Publication Series, 48 (2007), 103-125.

Derived functor modules arising as large constituents of degenerate principal series
(with Hisayosi Matumoto) pdf
Compositio Mathematica, 143 (2007), 222-256.

Shimura correspondences for split real groups
(with Jeffrey Adams, Dan Barbasch, Annegret Paul, and David Vogan) pdf
Journal of the American Math Society, 20 (2007), 701-751.

Kazhdan-Lusztig algorithms for nonlinear Lie groups and applications to Kazhdan-Patterson lifting
(with David Renard) pdf
American Journal of Mathematics, 127 (2005), 911-971.

Symplectic and orthogonal Robinson-Schensted algorithms pdf
Journal of Algebra, 286 (2005), 386-404.

Richardson orbits for real groups pdf
Journal of Algebra, 286 (2005), 361-385.

Some small unipotent representations of indefinite orthogonal groups pdf
Journal of Functional Analysis, 213 (2004), 290-320.

Special unipotent representations and the Howe correspondence pdf
University of Aarhus Publication Series, 47 (2004), 210-230.

Irreducible genuine characters of the metaplectic group II: Functoriality
(with David Renard) pdf
Journal für die reine und angewandte Mathematik, volume 557 (2003), 121-158.

One dimensional representations of U(p,q) and the Howe correspondence
(with Annegret Paul) pdf
Journal of Functional Analysis, 195 (2002), no. 1, 129--166.

Annihilators and associated varieties of A_q(lambda) modules for U(p,q) pdf
Compositio Mathematica, 129 (2001), no. 1, 1-45.

Irreducible genuine characters of the metaplectic group: Kazhdan-Lusztig algorithm and Vogan duality
(with David Renard) pdf
Representation Theory, 4 (2000), 245--295.

Nash equilibria for an evolutionary language game
(with Martin Nowak) pdf
Journal of Mathematical Biology, 41 (2000), no. 2, 172--188.

Representations of semisimple Lie groups
(with Anthony W. Knapp) pdf
in Representation theory of Lie groups (Park City, UT, 1998),
IAS/Park City Mathematical Series, 8 (2000), 7-87.

Generalized Robinson-Schensted algorithms for real Lie groups pdf
International Math Research Notices, 1999, no. 15, 803-834.

The adjoint representation in rings of functions
(with Eric Sommers) pdf 
Representation Theory1 (1997), 182-189.

Fourier series of radial functions in several variables,
(with Mark Pinsky and Nancy Stanton) ps
Journal of Functional Analysis116 (1993), no. 1, 111-132.

Back to the top.



Some lecture notes:


Parametrizing even real nilpotent orbits using ATLAS pdf
Unpublished notes from a lecture at University of Maryland workshop, March, 2008. A few small corrections made in 2017.

Notes on cells and special unipotent representations pdf
Unpublished notes from a lecture at an AIM workshop, July, 2007.
Based partially on notes taken by Patrick Polo. I made some small correctionsin 2017.

On the computation of characteristic cycles of Harish-Chandra modules pdf
Unpublished notes from a lecture an AIM workshop, July, 2006.

Computing Real Weyl Groups pdf
Unpublished notes from a lecture given by David Vogan at an AIM work shop, July, 2006.

Computing K-type multiplicities in standard modules (after Vogan) pdf
Unpublished notes from lectures at an AIM workshop, July, 2005.

Branching Laws pdf
Unpubilshed notes from an AIM workshop, July, 2003.
Notes by David Vogan.

Unitary representations of U(p,q) pdf
Notes from a talk at the AMS-SRC conference "Representation theory of real and p-adic reductive groups"
University of Washington, July, 1997.

Back to the top.



Some slides:


Cohomological Induction pdf
Slides from a talk at a 2017 Atlas of Lie Groups workshop.

Relations between unitary representations of real and p-adic groups,
Slides from my talk at David Vogan's Birthday Conference, 2014.

Kazhdan-Lusztig-Vogan polynomials and applications pdf
Slides from a Colloquium at the University of Washington, October, 2007.

Matching Kazhdan-Lustzig polynomials for GL(n,F) pdf
Slides from a lecture at an AIM workshop, July, 2007.

Starting a High School Math Circle
Slides from an invited address at an MAA meeting, March, 2006.
In ppt format ppt

Back to the top.



Some conferences I helped organize:


SL(2,R) Minicourse (May 2006)
(with Casselman and Milicic)
Minicourse Homepage

Representation Theory of Real Lie Groups (June 2006, Snowbird UT)
(with Arthur and Schmid)
Conference Homepage
Conference Proceedings (coedited with Arthur and Schmid): published in the AMS series Contemporary Mathematics, volume 472, 2008.

Representations of Reductive Groups (May 2014, MIT)
(with Bezrukavnikov, Etingof, Lusztig, and Nevins))
Conference Homepage
Conference Proceedings (coedited with Nevins): publihsed in the Birkhauser/Springer Progress in Mathematics book series (PM, volume 312)

Back to the top.



Some students:


Scott Crofts, PhD 2009: Duality for the universal cover of Spin(2n+1,2n).

Casey Johnson, PhD 2010: Enhanced nilpotent representations of a cyclic quiver.

Ben Trahan, PhD 2011: Functors for real and p-adic metaplectic groups.

Matt Housley, PhD 2011: Polynomial representations and associated cycles of indefinite unitary groups.

Kei Yuen Chan, PhD 2014: Extensions between modules for the graded affine Hecke algbera.

Adam Brown, PhD 2019: Arakawa-Suzuki functors for Whittaker modules.

Sean McAfee, PhD 2019: Twisted cells for real reductive groups.

In progress: Chengyu Du,

Back to the top.



Some miscellanea:


In Math, Confidence Doesn't Count
An op-ed piece for the Salt Lake Tribune html

Representation Theory
an electronic journal of the AMS

Back to the top.

The above material is based upon work partially supported by NSF grants DMS-0071606, DMS-0300106, DMS-0554118, DMS-0968275, DMS-0968060, and DMS-1302237, NSA Grant MSFP-06Y-095, and the Simons Foundation.