Sarah Witherspoon
Curriculum Vitae
Department of Mathematics
Texas A&M University
3368 TAMU
College Station, TX 778433368
email: sjw at tamu.edu,
web: people.tamu.edu/~sjw
Education
Ph.D., Mathematics, University of Chicago, 1994, Advisor: Dr. J. L. Alperin
S.M., Mathematics, University of Chicago, 1991
B.S., Mathematics, Arizona State University, 1988
Grants and Fellowships
Fellow of the American Mathematical Society, Class of 2018
NSF Individual Research Grant, Sept. 2020August 2024
American Institute of Mathematics Structured Quartet Research Ensemble
(AIM SQuaRE),
201822
NSF Individual Research Grant, Sept. 2017August 2020
NSF Individual Research Grant, Sept. 2014August 2017
NSA Conference Grant (coPIs Lars Christensen, Louiza Fouli,
David Jorgensen, Laura Matusevich),
Jan. 2014Dec. 2014
NSF PanAmerican Advanced Studies Institute Grant (PI Srikanth Iyengar, UNL),
Jan. 2012Dec. 2012
NSF Collaborative Research Grant (coPI Anne Shepler, UNT),
Sept. 2011August 2014
NSF Collaborative Research Grant (coPI Anne Shepler, UNT),
Sept. 2008August 2012
Texas Advanced Research Program Grant (coPI Anne Shepler, UNT),
May 2008May 2010
NSA Individual Research Grant, February 2007February 2009
Humboldt Foundation Research Fellowship, August 2005July 2006
NSF Individual Research Grant,
July 2003June 2006
NSA Individual Research Grant,
April 2001October 2003
NSF Research Grant
(PI: Georgia Benkart), May 1999June 2000
NSERC Individual Research Grant,
April 1995June 1998
Employment
Research Professor, SLMath, Spring 2024
Head of the Department of Mathematics, Texas A&M University, 201923
Professor, Texas A&M University, September 2010present
Research Professor, Mathematical Sciences Research Institute, Spring 2013
Associate Professor, Texas A&M University, September 2006August 2010
Assistant Professor, Texas A&M University, July 2004August 2006
Visiting Assistant Professor, Amherst College, July 2001December 2003
Visiting Assistant Professor, University of Massachusetts, Amherst,
Sept. 2000August 2001
Visiting Assistant Professor, Mount Holyoke College, Spring 2001
Van Vleck Assistant Professor, University of Wisconsin, Madison,
January 1999June 2000
Visiting Assistant Professor, Mills College, Fall 1996
Assistant Professor, University of Toronto, 19941998 (on leave at MSRI 19961997)
Graduate Teaching Assistant, University of Chicago, 19901993
Teaching Experience
Calculus, Finite Mathematics, Structure of Mathematics, Geometry,
Algebra, Commutative and Homological Algebra, Representation Theory,
Directed Studies and Research,
Texas A&M University, 2004present (Math 166, 171, 172, 220, 365, 366, 367,
415, 416, 653, 654,
662, 685, 689, 691)
Calculus, Chaotic Dynamical Systems, and Topology,
Amherst College, Spring 2001Fall 2003
Calculus, Mount Holyoke College, Massachusetts, Spring 2001
Basic Mathematics Skills and Honors Calculus for the Life and
Social Sciences, University of Massachusetts, Amherst, 20002001
Ring Theory, Finite Mathematics, and Linear Algebra, University of
Wisconsin, Madison, 19992000
Abstract Algebra, Linear Algebra, and Calculus, University of Toronto,
19941996 and 19971998
Linear Algebra, Mills College, Oakland, CA, Fall 1996
Precalculus, University of Chicago, 19901993
Refereed Publications
1.
The ring of equivariant vector bundles on finite sets,
J. Algebra
175 (1995), 274286.
2.
The representation ring of the quantum double of a finite group,
J. Algebra
179 (1996), 305329.
3.
The representation ring of the twisted quantum double of a finite group,
Canad. J. Math.
48 (1996), 13241338.
4.
Irreducible representations of crossed products (with Susan Montgomery),
J. Pure Appl. Algebra
129 (1998), 315326.
5. The Hochschild cohomology ring of a group algebra (with Stephen F. Siegel),
Proc. London Math. Soc.
79 (1999), 131157.
6. The representation ring and the centre of a Hopf algebra,
Canad. J. Math.
51 (1999), 881896.
7.
Clifford correspondence for finitedimensional Hopf algebras,
J. Algebra
218 (1999), 608620.
8.
A moduletheoretic approach to Clifford theory for blocks,
Proc. Amer. Math. Soc.
128 (2000), 661670.
9.
The Hochschild cohomology ring of a cyclic block
(with Stephen F. Siegel),
Proc. Amer. Math. Soc. 128 (2000), 12631268.
10.
A Hopf structure for downup algebras (with Georgia Benkart),
Math. Z. 238 (2001), 523553.
11.
Clifford correspondence for algebras, J. Algebra
256 (2002), 518530.
12.
Hochschild cohomology and Linckelmann cohomology for blocks
of finite groups (with Jonathan Pakianathan),
J. Pure Appl. Algebra 178 (2003), 87100.
13.
Algebraic deformations arising from orbifolds with discrete torsion
(with A. Caldararu and A. Giaquinto),
J. Pure Appl. Algebra 187 (2004), no. 13, 5170.
14.
Representations of twoparameter quantum groups and SchurWeyl duality
(with G. Benkart),
Hopf algebras, 6592,
Lecture Notes in Pure and Appl. Math.,
237, Dekker, New York, 2004.
15.
Restricted twoparameter quantum groups
(with G. Benkart), Representations of finite dimensional
algebras and related topics in Lie theory and geometry, 293318,
Fields Inst. Commun. 40 ,
Amer. Math. Soc., Providence, RI, 2004.
16.
Products in Hochschild cohomology and Grothendieck rings of group
crossed products, Adv. Math. 185
(2004), no. 1, 136158.
17.
Twoparameter quantum groups and Drinfel'd doubles
(with G. Benkart), Algebras and Representation Theory
7 (2004), 261286.
18.
Quillen stratification for Hochschild cohomology of blocks
(with J. Pakianathan and an appendix by S. Siegel), Trans. Amer. Math. Soc.
358 (2006), no. 7, 28972916.
19.
Skew derivations and deformations of a family of group crossed products,
Comm. Algebra 34 (2006), no. 11, 41874206.
20.
Quantum group actions, twisting elements, and deformations of algebras
(with G. Benkart), J. Pure Appl. Algebra 208
(2007), 371389.
21.
Twisted graded Hecke algebras,
J. Algebra 317 (2007), 3042.
22.
Hochschild cohomology of smash products and rank one Hopf algebras
(with Sebastian Burciu), Biblioteca de la Revista Matematica Iberoamericana
Actas del "XVI Coloquio Latinoamericano de Algebra"
(Colonia, Uruguay, 2005), 2007, 153170.
23.
Braid group representations from twisted quantum doubles of finite groups
(with Pavel Etingof and Eric Rowell), Pacific J. Math.
234 (2008), no. 1, 3341.
24.
Hochschild cohomology and graded Hecke algebras
(with Anne V. Shepler), Trans. Amer. Math. Soc. 360
(2008), no. 8, 39754005.
25.
Bialgebra cohomology, pointed Hopf algebras, and deformations
(with Mitja Mastnak), J. Pure Appl. Algebra 213
(2009), 13991417.
26.
Hopf quivers and Nichols algebras in positive characteristic
(with Claude Cibils and Aaron Lauve), Proc. Amer. Math. Soc.
137 (2009), no. 12, 40294041.
27.
Fusion subcategories of representation categories of twisted quantum doubles of finite groups
(with Deepak Naidu and Dmitri Nikshych), Int. Math. Res. Not.
22 (2009), 41834219.
28.
Varieties for modules of quantum elementary abelian groups
(with Julia Pevtsova), Algebras and Rep. Th.
12 (2009), no. 6, 567595.
29.
Cohomology of finite dimensional pointed Hopf algebras
(with Mitja Mastnak, Julia Pevtsova, and Peter Schauenburg),
Proc. London Math. Soc. (3) 100 (2010), no. 2, 377404.
30.
Support varieties and representation type of small quantum groups
(with Joerg Feldvoss),
Int. Math. Res. Not. (2010), no. 7, 13461362.
Erratum,
Int. Math. Res. Not. (2015), no. 1, 288290.
31.
YetterDrinfeld modules under cocycle twists
(with Georgia Benkart and Mariana Pereira),
J. Algebra 324 (2010), no. 11, 29903006.
32.
Hochschild cohomology of group extensions of quantum symmetric algebras
(with Deepak Naidu and Piyush Shroff),
Proc. Amer. Math. Soc. 139 (2011), no. 5, 15531567.
33.
Finite groups acting linearly: Hochschild cohomology and the cup product
(with Anne V. Shepler),
Advances in Math. 226 (2011), no. 4, 28842910.
34.
Quantum differentiation and chain maps of bimodule complexes
(with Anne V. Shepler),
Algebra and Number Theory 53 (2011), 339360.
35.
Support varieties and representation type of selfinjective algebras
(with Joerg Feldvoss),
Homology, Homotopy and Applications 13 (2011), no. 2,
197215.
36.
Group actions on algebras and the graded Lie structure of Hochschild
cohomology
(with Anne V. Shepler),
J. Algebra 351 (2012), 350381.
37.
Drinfeld orbifold algebras
(with Anne V. Shepler),
Pacific J. Math. 2591 (2012), 161193.
38.
Examples of support varieties for Hopf algebras
with noncommutative tensor products
(with Dave Benson),
Archiv der Mathematik
102 (2014), no. 6, 513520.
39.
A PoincareBirkhoffWitt Theorem for quadratic algebras with group actions
(with Anne V. Shepler),
Trans. Amer. Math. Soc.
366 (2014), no. 12, 64836506.
40.
Finite generation of the cohomology of some skew group algebras
(with Van C. Nguyen),
Algebra and Number Theory
8 (2014), no. 7, 16471657.
Correction Algebra and Number Theory 12 (2018), no. 2, 491492.
41.
PoincareBirkhoffWitt deformations of smash product algebras from
Hopf actions on Koszul algebras
(with Chelsea Walton),
Algebra and Number Theory 8 (2014), no. 7, 17011731.
42.
PBW deformations of skew group algebras in positive characteristic
(with Anne V. Shepler), Algebras and Representation
Theory 18 (2015), no. 1, 257280.
43.
Tensor ideals and varieties for modules of quantum elementary abelian groups
(with Julia Pevtsova), Proceedings of the American
Mathematical Society 143 (2015), no. 9, 37273741.
44.
PoincareBirkhoffWitt Theorems
(with Anne Shepler), in Mathematical Sciences Research
Institute Proceedings Commutative Algebra and Noncommutative
Algebraic Geometry, Vol. 1, ed. D. Eisenbud, S. B. Iyengar, A.K. Singh, J. T. Stafford, and M. Van den Bergh, Cambridge Univ. Press, 2015.
45.
An alternate approach to the Lie bracket on Hochschild cohomology
(with Cris Negron), Homology, Homotopy and Applications
18 (1) (2016), 265285.
46.
PBW deformations of quantum symmetric algebras and their group extensions
(with Piyush Shroff), J. Algebra and Its Applications 15
(2016), no. 3, 15 pp.
47.
Hopf automorphisms and twisted extensions
(with Susan Montgomery and Maria D. Vega),
J. Algebra and Its Applications 15 (2016), no. 6, 14 pp.
48.
Gerstenhaber brackets on Hochschild cohomology of quantum symmetric algebras and their group extensions
(with Guodong Zhou), Pacific J. Math. 283 (2016), no. 1,
223255.
49.
Hochschild cohomology and quantum Drinfeld Hecke algebras
(with Deepak Naidu),
Selecta Mathematica 22 (2016), no. 3, 15371561.
50.
The Gerstenhaber bracket as a Schouten bracket for polynomial rings extended by finite groups (with Cris Negron),
Proc. Lond. Math. Soc. (3) 115 (2017), no. 6, 11491169.
51.
Gerstenhaber brackets on Hochschild cohomology of twisted
tensor products
(with Lauren Grimley and Van C. Nguyen),
J. Noncommutative Geometry 11 (2017), no. 4, 13511379.
52.
Tensor products and support varieties for some noncocommutative Hopf algebras (with Julia Plavnik),
Algebr. Represent. Theory 21 (2018), no. 2, 259276.
53.
PBW deformations of braided products (with Chelsea Walton),
J. Algebra 504 (2018), 536567.
54.
Deforming group actions on Koszul algebras
(with Anne Shepler), Mathematical Research Letters
25 (2018), no. 5, 16131644.
55.
Varieties for modules of finite dimensional Hopf algebras,
Geometrical and Topological Aspects of the Representation
Theory of Finite Groups,
Pacific Institute for the Mathematics Sciences
Summer School and Workshop, July 27August 5, 2016,
Springer 2018, 481495.
56.
Finite generation of some cohomology rings via twisted tensor product
and Anick resolutions (with Van C. Nguyen and Xingting Wang),
J. Pure Appl Algebra 223 (2019), no. 1, 316339.
57.
Color Lie rings and PBW deformations of skew group algebras
(with S. Fryer, T. Kanstrup, E. Kirkman, and A.V. Shepler),
Journal of Algebra 518 (2019), 211236.
58.
Resolutions for twisted tensor products
(with Anne Shepler), Pacific J. Math 298 (2019), no. 2, 445469.
59.
A_{∞}coderivations and the Gerstenhaber bracket on Hochschild cohomology
(with C. Negron and Y. Volkov), J. Noncommutative Geometry 14 (2020), no. 2, 531565.
60.
Gerstenhaber brackets on Hochschild cohomology of general
twisted tensor products
(with T. Karadag, D. McPhate, P. Ocal, and T. Oke),
J. Pure Appl. Algebra 225 (2021), no. 6, 14 pp.
61.
Support varieties for finite tensor categories:
Complexity, realization, and connectedness
(with P. A. Bergh and J. Y. Plavnik),
J. Pure Appl. Algebra 225 (2021), no. 9, 21 pp.
62.
Grouptwisted AlexanderWhitney and EilenbergZilber maps
(with A.V. Shepler), Algebras and Representation Theory 24 (2021), no. 2, 357366.
63.
New approaches to finite generation of cohomology rings
(with V.C. Nguyen and X. Wang), J. Algebra 587 (2021), 390428.
64.
Cohomology rings of finitedimensional pointed Hopf algebras
over abelian groups
(with N. Andruskiewitsch, I. Angiono, and J. Pevtsova),
Research in the Mathematical Sciences 9 (2022), no. 1,
Paper No. 12, 132 pp.
65.
Gerstenhaber brackets for skew group algebras in positive characteristic
(with A.V. Shepler), Transformation Groups 27 (2022), no. 1,
295309.
66.
Lie brackets on Hopf algebra cohomology
(with T. Karadag), Pacific J. Math. 316 (2022), no. 2, 395407.
67.
Hochschild cohomology of twisted tensor products
(with B. Briggs) Math. Z. 301 (2022), no. 2, 12371257.
68.
Homotopy liftings and Hochschild cohomology of some twisted tensor products
(with P. Ocal and T. Oke) J. Algebra and Its Applications 21 (2022),
no. 12, Paper No. 2250238, 16 pp.
69.
Delta sets and polynomial identities in pointed Hopf algebras
(with Y. Bahturin) Algebras and Representation Theory 26 (2023), no. 1,
97116.
Other Publications
 Derivatives, Derivations, and Hochschild Cohomology,
Introduction to Invited Address at the AMS Fall Western
Sectional Meeting,
AMS Notices 65 (2018), No. 9,
p. 1078.
 Hochschild Cohomology for Algebras,
Graduate Studies in Mathematics 204, American Mathematical Society, 2019.
 Hochschild Cohomology,
AMS Notices 67 (2020), No. 6, pp. 780787.
Department and University Service
Graduate Students:
 Mariana Pereira, PhD 2006
 Jeanette Shakalli, PhD 2012
 Piyush Shroff, PhD 2012
 Stephanie Tougas, Masters 2010
 Heather Williamson, Masters 2012
 Van Nguyen, PhD 2014
 Lauren Grimley, PhD 2016
 Hao Xing, Masters 2018
 Dustin McPhate, PhD 2021
 Tekin Karadag, PhD 2021
 Pablo Sanchez Ocal, PhD 2021
 Tolulope Oke, PhD 2021
Postdocs Mentored:
 Aaron Lauve, 200810
 Deepak Naidu, 200911
 Chelsea Walton, Spring 2013 (MSRI Postdoc)
 Julia Plavnik, 201518
Committees:
 Member, Graduate Committee, Fall 2006Summer 2010, and Mentoring Subcommittee,
December 2008Summer 2010
 Member, Maxson Lectures Committee, Spring 2007 and Fall 2011Spring 2014
 Member, Mathematics Awareness Month Committee, Spring 2007 (Coorganized the Integral
Bee, April 16, 2007)
 Member, Subcommittee T, Spring 2009Fall 2011
 Member, Undergraduate Committee, Fall 2010Fall 2012
 Member, Subcommittee L, Spring 2012Spring 2014
 Member, Executive Committee, Fall 2013Spring 2015
 Chair, Postdoc Committee, Fall 2015
 Member, College of Science Tenure and Promotion Committee, 201516
and 201718
 Awards Committee, Fall 2017present (Chair 201718)
Miscellaneous:
 Organizer, Working Algebra Seminar, Fall 2008 and Spring 2010 (with Aaron Lauve)
 Coorganizer, First Year Graduate Student
Seminar, September 2009December 2010
 Coorganizer, Algebra and Combinatorics Seminar, Fall 2010 (with Deepak Naidu), Spring and Fall 2012 (with Catherine Yan),
Spring 2014 (with Jacob White), Fall 2018 (with Catherine Yan and
Yue Cai)
 SEE Math: gave 3 lectures to middle school students, July 21 and 22, 2008
 Math Circle (middle and high school students):
logistical support, Fall 2014
 Aggieland Saturday presentation to high school students and parents,
February 14, 2015
Professional Service
Professional Societies:
 AMSMAASIAM Committee on Employment Opportunities,
February 2006January 2009 (Chair February 2008January 2009)
 MemberatLarge of the AMS Council, February 2008January 2011
 AMS Committee on Education, February 2008January 2011
 AMS Working Group on the Nominee Program, January 2010January 2011
 AMS Travel Grants Committee, January 2011December 2013
 AMS Centennial Fellowship Committee, December 2013December 2015
 AWM JMM Subcommittee, February 2017January 2019
 MSRI Human Resources Advisory Committee, April 2017March 2020
 AMS Central Program Committee, February 2019January 2021
Organization:
 Organizing Committee, AMSIMSSIAM Joint Summer Research Conference
on Groups, Representations, and Cohomology, Mount Holyoke College,
Massachusetts, June 713,2002
 Coorganizer, Special Session on Hopf Algebras and Quantum Groups
at the AMS Sectional Meeting in New York City, April 1213, 2003
 Coorganizer, Banff International Research Station Workshop
on Hochschild Cohomology of Algebras: Structure and Applications,
Banff, Alberta, Canada, September 27, 2007
 Coorganizer, AMSAWM Special Session on Hopf Algebras and Their
Representations
at the Joint Mathematics Meetings in New Orleans, January 8, 2011
 Coorganizer, PanAmerican Advanced Studies Institute: Commutative
Algebra and Its Interactions with Algebraic Geometry, Representation Theory.,
and Physics, Guanajuato, Mexico, May 1425, 2012
 Coorganizer, MiniWorkshop on Nichols Algebras and Weyl Groupoids,
Oberwolfach, Germany, September 30October 6, 2012
 Coorganizer, Southwest Local Algebra Meeting, College Station, Texas,
March 12, 2014
 Coorganizer, AMS Special Session on Noncommutative Algebra, Deformations,
and Hochschild Cohomology at the AMS Sectional Meeting in Lubbock, Texas, April 1113, 2014
 Coorganizer, AMS Special Session on Hopf Algebras and Tensor Categories
at the Joint Mathematics Meetings in San Antonio, Texas, January 1213, 2015
 Coorganizer, Banff International Research Station Workshop on
Nichols Algebras and Their Interactions with Lie Theory, Hopf Algebras and Tensor Categories,
Banff, Alberta, Canada, September 611, 2015
 Coorganizer, AMS Special Session on
Noncommutative and Homological Algebra at the AMS Sectional Meeting in Denton, Texas, September 910, 2017
 Coorganizer, Association for Women in Mathematics Workshop, Joint Mathematics Meetings, January 13, 2018
 Coorganizer, AMS Special Session on
Hopf Algebras, Tensor Categories, and Homological Algebra at
the AMS Sectional Meeting in Boston, Massachusetts, April 2122, 2018
 Coorganizer, Stable Cohomology: Foundations and Applications,
Snowbird, Utah, May 28June 1, 2018
 Coorganizer, AMS Special Session on Homological Aspects of Noncommutative Algebra and Geometry at the AMS Sectional Meeting in San Francisco, California, October 2728, 2018
 Coorganizer, MiniWorkshop on Cohomology of Hopf Algebras and Tensor Categories, Oberwolfach, Germany, March 39, 2019
 Coorganizer, AMS Special Session on Interactions Between
Noncommutative Algebra and Noncommutative Algebraic Geometry
at the Joint Mathematics Meetings (online), January 9, 2021
Editorial Activities:
 Editorial Board, Journal of Algebra (special issue
dedicated to Georgia Benkart), 2023
 Editorial Board, Proceedings of the American Mathematical
Society, February 2019present
 Editorial Board, Communications in Algebra, October 2016present
 Editorial Board, Algebras and Representation Theory,
March 2017December 2018
 Editorial Board, Quaestiones Mathematicae, September 2011December 2017
 Editor, AMS Contemporary Mathematics: Proceedings of the Conference
on Group Theory, Combinatorics, and Computing, October 38, 2012.
Refereeing and Reviewing:
 Moderator, arXiv, 20162019
 Reviewer, Math Reviews, 20042016
 Referee/Panels, NSA and NSF
 Referee, Adv. Math., Algebra Colloq., Algebra and Number Theory,
Algebras and
Rep. Th., Archiv der Mathematik, Bull. LMS,
Commun. Algebra, Contemp. Math.,
Frontiers of Math. in China,
International J. Math.,
IMRN, Israel J. Math.,
J. Algebra, J. Algebra and Its Applications,
J. Algebras and Representation Th.,
J. London Math. Soc., J. Math. Phys., J. Noncommut. Geom.,
J. Pure Appl. Algebra, Math. Notes, Math. Proc. Royal Irish Acad.,
Portugaliae Math.,
Proc. AMS, Proc. LMS, Rocky Mtn. Math. J., Trans. SIGMA, Amer. Math. Soc., Transformation Groups
Talks
Conference Talks:
 The quantum double of a finite group, NATO ASI on Finite and
Locally Finite Groups, Istanbul, August 26, 1994.
 A moduletheoretic approach to Clifford theory for blocks, AMS
Special Session, Kent, Ohio, November 4, 1995.
 Irreducible representations of crossed products,
AMS Summer Research Institute on Cohomology, Representations,
and Actions of Finite Groups, Seattle, July 17, 1996.
 Irreducible representations of crossed products, AMS Special Session
on Hopf Algebras and Their Representations, Caltech, November 17, 1996.
 Clifford theory for Hopf algebras, Southern California
Algebra Conference, UCLA, April 12, 1997.
 The Hochschild cohomology ring of a finite group, Colloque de Luminy,
Methodes Homologiques et Representations de Groupes, Luminy, France, July 3,
1997.
 The Hochschild cohomology ring of a group algebra: Connections
with the quantum double, AMS Special Session on Representations of
Finite Groups , Baltimore, January 9, 1998.
 A Hopf structure for downup algebras, MSRI Hopf Algebras Workshop,
Berkeley, October 27, 1999.
 Downup algebras and twoparameter quantum groups,
AMSCMS Special Session on Representations of Infinite Dimensional
Lie Algebras, Toronto, September 23, 2000.
 Hochschild cohomology and Linckelmann cohomology for blocks of
finite groups, AMS Special Session, New Orleans, January 12, 2001.
 Clifford correspondence for Hopf algebras,
International Hopf Algebras Conference, DePaul University,
Chicago, February 1, 2002.
 Hochschild cohomology and representations of crossed products,
AMS Special Session on Ring Theory, Madison, Wisconsin, October 12, 2002.
 Algebraic deformations arising from an orbifold with discrete torsion,
AMS Special Session on
Algebras, Actions, and Algorithms, Baltimore, January 15, 2003.
 Hochschild cohomology of crossed products,
Workshop on Representation Theory,
Australian National University, June 30, 2003.
 Ring structures of Hochschild and orbifold cohomology,
AMS Special Session on Group Cohomology and Related Topics,
Lawrenceville, New Jersey, April 17, 2004.
 Algebraic deformations arising from quantum group actions,
Lie Groups, Lie Algebras, and their Representations Workshop,
University of California, Santa Cruz, April 24, 2004.
 Deformations arising from quantum group actions on algebras,
CMS Session on Hopf Algebras and Related Topics,
Halifax, June 14, 2004.
 Quantum group actions, Rmatrices, and deformations of algebras,
AMS Special Session on Algebraic Representations and Deformations,
Evanston, IL, October 24, 2004.
 Deformations of crossed products and graded Hecke algebras,
Red Raider MiniSymposium on Invariant Theory in Perspective,
Texas Tech, November 12, 2004.
 Varieties for modules of noncocommutative Hopf algebras,
AMS Special Session on Hopf Algebras and Related Topics,
Bowling Green, Kentucky, March 19, 2005.
 Skew derivations and deformations of algebras,
AMSDMVOMV Special Session on Hopf Algebras and Quantum Groups,
Mainz, Germany, June 17, 2005.
 Graded Hecke algebras and Hochschild cohomology,
Session on Homological Methods and Representation Theory at
the XVI Coloquio Latinoamericano de Algebra,
Colonia, Uruguay, August 4, 2005.
 Varieties for modules of quantum elementary abelian groups,
AMS Special Session on Cohomology and Representation Theory,
New Orleans, January 5, 2007.
 Braid group representations from twisted quantum doubles
of finite groups, AMS Special Session on Hopf Algebras and
Related Areas,
Chicago, October 6, 2007.
 Quantum groups and pointed Hopf algebras, University
of California Lie Theory Workshop in Honor of Georgia Benkart,
San Diego, February 18, 2008.
 Cohomology of finite dimensional pointed Hopf algebras,
AMS Special Session on Hopf Algebras and Quantum Groups,
Claremont, California, May 4, 2008.
 Cohomology of pointed Hopf algebras,
Rencontre Mathematique, Homologie des algebres: structures et applications,
CIRM Luminy, France, December 2, 2008.
 Nichols algebras in positive characteristic,
AMS Special Session on Noncommutative Algebra,
Washington, DC, January 6, 2009.
 Fusion subcategories of Rep(D(G)),
Colloquium on Hopf Algebras, Quantum Groups, and Tensor Categories,
La Falda, Argentina, September 4, 2009.
 Representation type and support varieties,
KUMUNU Regional Conference,
Lincoln, Nebraska, September 19, 2009.
 Fusion subcategories of Rep(D(G)),
AMS Special Session on Fusion Categories and Applications,
Waco, Texas, October 17, 2009.
 Support varieties and representation type,
AMS Special Session on Categorical and Algebraic Methods
in Representation Theory,
San Francisco, California, January 16, 2010.
 Quantum symmetric algebras,
Southwest Local Algebra Meeting,
Arlington, Texas, March 7, 2010.
 Graded Hecke algebras and deformations of crossed products,
AMS Special Session on Hecke Algebras and Deformations in Geometry
and Topology,
St. Paul, Minnesota, April 11, 2010.
 Support Varieties and Representation Type,
Colloque de Luminy, Cohomologie de Hochschild, structure et applications,
Luminy, France, June 11, 2010.
 Deformations of Skew Group Algebras and Orbifolds,
New Trends in Noncommutative Algebra, A Conference in Honor
of Ken Goodearl's 65th Birthday,
Seattle, Washington, August 12, 2010.
 Deformations of Skew Group Algebras,
NSF/CBMS Conference on Deformation Theory of Algebras and Modules,
Raleigh, North Carolina, May 17, 2011.
 Generalizations of Drinfeld Hecke Algebras,
Session on Group Theory and its Connections with Representation Theory,
at 40 Years and Counting: AWM's Celebration of Women in Mathematics,
Providence, Rhode Island, September 17, 2011.
 Hochschild Cohomology and Support Varieties,
threelecture series at the
Workshop on Representation Theory: Cohomology and Support,
Beijing, China, September 2630, 2011.
 Hochschild cohomology of crossed products: ring
and graded Lie structure,
Interactions between Commutative Algebra and Representation
Theory: A Conference in Honor of RagnarOlaf Buchweitz'
Sixtieth Birthday,
Syracuse University, New York, April 14, 2012.
 Is the cohomology of a finite dimensional Hopf algebra
finitely generated?
Lie Theory Workshop,
University of Southern California, Los Angeles, May 5, 2012.

Varieties for modules of Hopf algebras,
Workshop on Cohomology and Support in Representation Theory and Related Topics,
University of Washington, Seattle, August 5, 2012.

Cohomology of Nichols algebras and Hopf algebras,
MiniWorkshop on Nichols Algebras and Weyl Groupoids,
Oberwolfach, Germany, October 3, 2012.

PoincareBirkhoffWitt Theorems,
MSRI Connections for Women: Noncommutative Algebraic Geometry and Representation Theory,
Berkeley, January 24, 2013.

PoincareBirkhoffWitt Theorems and group actions in positive characteristic,
MSRI Workshop: Interactions between Noncommutative Algebra, Representation Theory,
and Algebraic Geometry,
Berkeley, April 8, 2013.
 PBW deformations and Hopf actions on Koszul algebras,
Workshop on Hochschild Cohomology: Structure and Applications,
Buenos Aires, Argentina, August 16, 2013.
 PBW deformations and Hopf algebra actions,
AMS Special Session on Recent Developments in Noncommutative Algebra,
Temple University, Philadelphia, October 13, 2013.
 Lie algebras, PoincareBirkhoffWitt theorems, and beyond,
Pacific Undergraduate Research Experiences in Mathematics,
Hilo, Hawaii, August 1, 2014.
 Hopf actions and PBW deformations,
AMS Special Session on Groups, Group Rings, and Hopf Algebras,
celebrating the 75th birthday of Donald S. Passman,
Loyola University, Chicago, October 2, 2015.
 The graded Lie structure of Hochschild cohomology,
AMS Special Session on Geometric and Categorical Methods in Representation Theory,
Joint Mathematics Meetings, Seattle, January 8, 2016.
 An alternate approach to the Lie bracket on Hochschild cohomology,
Workshop on Hochschild Cohomology in Algebra, Geometry, and Topology,
Oberwolfach, Germany, February 17, 2016.
 Support varieties for Hopf algebras,
PIMS Workshop on Geometric and Topological Aspects of the
Representation Theory of Finite Groups,
UBC, Vancouver, Canada, August 3, 2016.
 Support varieties for Hopf algebras,
BIRS Workshop on Bridges Between Noncommutative Algebra and Algebraic Geometry,
BIRS, Banff, Canada, September 12, 2016.
 The Lie structure on Hochschild cohomology, with motivation
from algebraic deformation theory,
Conference in Honor of Ellen Kirkman and Martin Lorenz,
Temple University, Philadelphia, Pennsylvania, July 25, 2017.
 Twisted tensor product algebras and resolutions,
AMS Special Session on Noncommutative Algebras and Noncommutative
Invariant Theory,
Joint Mathematics Meetings, San Diego, California, January 12, 2018.
 From groups to Hopf algebras: Cohomology and varieties for modules,
Connections for Women: Group Representation Theory and Applications,
MSRI, Berkeley, California, February 2, 2018.
 Tate and TateHochschild cohomology of Hopf algebras,
Workshop on Stable Cohomology,
Snowbird, Utah, May 28, 2018
 Derivatives, Derivations, and Hochschild Cohomology,
Invited Address,
AMS Fall Western Sectional Meeting,
October 27, 2018.
 Finite generation conjecture for finite dimensional
Hopf algebras and finite tensor categories,
MiniWorkshop on Cohomology of Hopf Algebras and Tensor Categories,
Oberwolfach, Germany, March 4, 2019.
 Hochschild cohomology of algebras,
threelecture series at the
Homotopy meets homology workshop,
Trinity College Dublin, Ireland,
May 2729, 2019.
 Hochschild cohomology as a graded Lie algebra,
Ragnar's Ramifications in Algebra and Geometry Emerging workshop,
Fields Institute, Toronto, Canada,
July 8, 2019.
 The Gerstenhaber bracket on Hochschild cohomology,
Homological Methods Session,
XXIII Coloquio Latinoamericano de Algebra,
Mexico City, Mexico, August 5, 2019.
 Varieties for representations and tensor categories,
Plenary Talk,
XXIII Coloquio Latinoamericano de Algebra,
Mexico City, Mexico, August 6, 2019.
 Hopf Algebras I and II,
Introductory Workshop: Quantum Symmetries,
MSRI, Berkeley, California, January 27 and 28, 2020.
 Varieties for representations and tensor categories,
International Conference on Representation Theory of Algebras
(Virtual),
November 20, 2020.
 Support varieties for finite tensor categories,
Recent Advances and New Directions in the Interplay of Noncommutative
Algebra and Geometry,
University of Washington, Seattle, June 21, 2022.
 Support varieties for finite tensor categories,
Representation Theory and Triangulated Categories:
A conference in honor of Henning Krause,
Paderborn, Germany, September 29, 2022
 Hopf algebras, monoidal categories, and cohomology,
Seattle Noncommutative Algebra Day,
University of Washington, Seattle, October 21, 2023
Colloquium Talks:
 From groups to Hopf algebras,
University of Saskatchewan, Canada, November 29, 1996.
 Kaplansky's conjectures on Hopf algebras,
University of California, Santa Cruz, February 11, 1997.
 Kaplansky's conjectures on Hopf algebras,
New Mexico State University, March 10, 1997.
 Finite groups and Mackey functors,
University of Southern California, April 9, 1997.
 Applications of finite group representation theory,
Texas A&M University, February 2, 1998.
 Representations of finite groups and Hopf algebras,
Loyola University Chicago, March 19, 1998.
 Group cohomology and Hochschild cohomology,
University of California, Santa Cruz, November 10, 1998.
 Representations of finite groups and Hopf algebras,
Northern Illinois University, De Kalb, November 12, 1999.
 From groups to Hopf algebras,
University of Wisconsin, Parkside, May 5, 2000.
 Knots and the Jones polynomial,
Amherst College, February 15, 2001.
 Knots and the Jones polynomial,
Mount Holyoke College, April 9, 2001.
 Cohomology in Algebra,
North Carolina State University, January 31, 2003.
 Cohomology in Algebra,
University of Colorado, February 2003.
 Cohomology in Algebra,
Texas A&M University, February 24, 2003.

Algebraic Deformation Theory,
University of Saskatchewan, March 18, 2003.

Cohomology in Algebra,
Virginia Tech, October 17, 2003.
 Cohomology and deformations of algebras,
Texas A&M University, April 26, 2005.
 Graded Hecke algebras and deformations of crossed products,
BristolLeicesterOxford Colloquium,
University of Oxford, UK, May 30, 2006.
 Dynkin diagrams in algebra: The old and the new,
Sam Houston University, April 4, 2007.
 Dynkin diagrams in algebra,
University of South Alabama, September 18, 2008.
 Hopf algebras: Structure and representations,
Texas A&M University, September 29, 2009.
 Representation Type and Varieties,
Northern Illinois University, February 16, 2012.
 Representation Type and Varieties,
DePaul University, February 17, 2012.
 Noncommutative Algebra and Geometry,
San Jose State University, April 17, 2013.
 Varieties for Modules,
University of California Berkeley, April 25, 2013.
 PoincareBirkhoffWitt Theorems,
University of TexasArlington, November 15, 2013.
 PoincareBirkhoffWitt Theorems,
Temple University, October 24, 2016.
 Derivatives, Derivations, and Hochschild Cohomology,
University of Texas Arlington, February 15, 2019.
Seminar Talks and Other Talks:
 Representations of symmetric groups, Pizza Seminar, University
of Chicago, May 10, 1991.
 Simple Lie algebras and groups of Lie type, Junior Seminar on
Groups and Geometries, University of Chicago,
April 17, 1991.
 The quantum double of a group algebra, Group Theory Seminar,
Michigan State University, March 23, 1993.
 The quantum double of a group algebra, Group Theory Seminar,
University of Chicago, May 20, 1993.
 Hopf algebras and quantum groups, Pizza Seminar,
University of Chicago, June 4, 1993.
 Representations of the quantum double of a finite group,
Algebra Seminar, Northwestern University, Evanston, Illinois,
November 2, 1993.
 Kaplansky's 10 conjectures on Hopf algebras, Pizza Seminar,
University of Chicago, December 3, 1993.
 Quantum doubles and Mackey functors, Group Theory Seminar,
University of Chicago, May 12, 1994.
 The quantum double of a finite group, Algebra Seminar, Purdue
University, May 27, 1994.
 Projective representations of the quantum double of a finite group,
PrincetonRutgers Group Theory Seminar, Princeton University,
February 14, 1995.
 Characters and representations, Applied Group Representations Seminar,
University of Toronto, April 4, 1995.
 The representation ring of the twisted quantum double of a finite group,
Algebra Seminar, University of Southern California, September 5, 1995.
 Representations of crossed products, Algebra Seminar,
McMaster University, Canada, November 15, 1995.
 Representations of Hopf algebras, Lie Groups Seminar,
University of Toronto, November 24, 1995.
 Errordetecting and errorcorrecting codes, Mathematical Science
Day, lecture to high school students, University of Toronto,
April 27, 1996.
 A conjecture of Kaplansky for finite dimensional Hopf algebras,
Quantum Groups Seminar, University of Waterloo, Canada, May 28, 1996.
 A conjecture of Kaplansky for finite dimensional Hopf algebras,
Seminar, Mount Allison University, Canada, June 26, 1996.
 A conjecture of Kaplansky for finite dimensional Hopf algebras,
Conformal Field Theory Seminar, University of California, Santa Cruz,
October 22, 1996.
 Irreducible representations of crossed products,
Lie Theory Seminar, University of Saskatchewan, Canada, November 30, 1996.
 Kaplansky's conjectures on Hopf algebras, Seminar,
Texas A&M University, March 5, 1997.
 Kaplansky's conjectures on Hopf algebras, Area III Seminar,
MSRI, Berkeley, April 2, 1997.
 Clifford theory for Hopf algebras, Commutative Algebra Seminar,
University of Illinois, UrbanaChampaign, May 1, 1997.
 The twisted quantum double of a finite group, Quantum Topology
Seminar, MSRI, Berkeley, May 9, 1997.
 The Hochschild cohomology ring of a finite group, Algebra Seminar,
University of California, Santa Cruz, May 30, 1997.
 Clifford correspondence for Hopf algebras,
Oberseminar Hopfalgebren,
Universitaet Muenchen, July 22, 1997.
 The Hochschild cohomology ring of a group algebra,
Ring Theory Seminar, University of Wisconsin, Madison, February 18, 1998.
 Hopf algebras and Kaplansky's conjecture, Noetherian Ring Seminar,
University of Wisconsin, Madison, February 19, 1998.
 Clifford theory, Ring Theory Seminar,
University of Wisconsin, Madison, March 31 and April 7, 1999.
 Alperin's weight conjecture, Group Theory Seminar,
University of Wisconsin, Madison, November 8 and 15, 1999.
 Mackey functors, Hochschild cohomology, and quantum doubles,
Learning Topology Seminar, University of Wisconsin, Madison,
November 8 and 15, 1999.
 A Hopf structure for downup algebras, Ring Theory Seminar,
University of Wisconsin, Madison, February 9 and 16, 2000.
 Introduction to quantum groups, Representation Theory Seminar,
University of Massachusetts, Amherst, September 18, 2000.
 Twoparameter quantum groups, Hecke algebra representations,
and SchurWeyl duality, Representation Theory Seminar, University of
Massachusetts, Amherst, September 25, 2000.
 Quantum groups, Drinfel'd doubles, and downup algebras,
Lie Theory Seminar, University of Wisconsin, Madison, March 20, 2001.
 Clifford correspondence, Number Theory Seminar,
Amherst College, October 2, 2001.
 Downup algebras, quantum groups, and SchurWeyl duality,
Group Theory Seminar, University of Chicago, January 31, 2002.
 Algebraic deformations arising from orbifolds with discrete torsion,
Lie Theory Seminar, University of Wisconsin, Madison, October 15, 2002.
 What is (co)homology?,
The "What Is . . . ?" Graduate Seminar,
University of Massachusetts, Amherst, November 20, 2002.
 Algebraic deformations arising from orbifolds,
Valley Geometry Seminar, University of Massachusetts, Amherst,
November 22, 2002.
 Hochschild cohomology and orbifolds,
Group Theory Seminar, Ohio State University, January 23, 2003.
 Hochschild cohomology and representations of crossed products,
Algebra and Logic Seminar,
University of Saskatchewan, March 20, 2003.
 Hochschild cohomology and deformations of crossed products,
Deformation Theory Seminar,
University of Pennsylvania, September 24, 2003.
 Cohomology and deformations of crossed products,
Representation Theory Seminar,
University of Massachusetts, November 10, 2003.
 Representations of the symmetric groups and cohomology,
Discrete Mathematics and Representation Theory Seminar,
University of California, Davis, March 5, 2004.
 Algebraic deformations arising from quantum group actions,
Algebra Seminar,
University of Oregon, April 27, 2004.
 Graded Hecke algebras and deformations of crossed products,
Lie Theory Seminar,
University of Wisconsin, Madison, October 26, 2004.
 Reflection groups and graded Hecke algebras,
Groups and Dynamics Seminar,
Texas A&M University, November 3, 2004.

Quantum groups and deformations of algebras,
Graduate Student Organization Seminar,
Texas A&M University, November 4, 2004.
 Representations of the symmetric groups and cohomology,
Algebra and Combinatorics Seminar,
Texas A&M University, February 18, 2005.
 Graded Hecke algebras and deformations of crossed products,
Algebra Seminar, University of Texas, Austin, May 3, 2005.
 Twisted graded Hecke algebras,
Group Theory Seminar, University of Chicago, May 12, 2005.
 Graded Hecke algebras and deformations of crossed products,
Algebra Seminar, DePaul University, Chicago, May 13, 2005.
 Hochschild cohomology, graded Hecke algebras, and Hopf algebra
actions, Oberseminar Hopfalgebren, Universitaet Muenchen,
December 5 and 9, 2005.
 Hochschild cohomology and graded Hecke algebras,
Geometry, Topology, and Algebra Seminar,
Universite de Montpellier II, France, March 30, 2006.
 Varieties for modules of finite groups and Hopf algebras,
Oberseminar Hopfalgebren,
Universitaet Muenchen, Germany, May 4 and 11, 2006.
 Quantum groups and pointed Hopf algebras,
Algebra and Combinatorics Seminar,
Texas A&M University, September 15, 2006.
 Quantum groups and pointed Hopf algebras,
Algebra and Algebraic Geometry Seminar,
University of Washington, May 15, 2007.
 Graded Hecke algebras and Hochschild cohomology, I and II,
Algebraic Representation Theory Seminar,
University of Minnesota, June 14 and 21, 2007.
 When is cohomology finitely generated?
Algebra and Combinatorics Seminar,
Texas A&M University, November 26, 2007.
 Cohomology of pointed Hopf algebras,
Algebra Seminar,
University of South Alabama, September 19, 2008.
 Algebras in tensor categories,
Working Algebra Seminar,
Texas A&M University, September 24 and October 1, 2008.
 Hopf algebras in braided monoidal categories,
Working Algebra Seminar,
Texas A&M University, November 5, 2008.
 Quantum symmetric algebras,
Algebra and Combinatorics Seminar,
Texas A&M University, November 7, 2008.
 The bilax structure of the chain complex functor,
Working Algebra Seminar,
April 10, 2009.
 Knots and the Jones polynomial,
Undergraduate Math Club Meeting,
Texas A&M University, April 20, 2009.
 Platonic solids and Euler characteristic,
Summer Mathematics Research Training Camp,
Texas A&M University, June 23, 2009.
 PoincareBirkhoffWitt algebras,
Working Algebra Seminar,
Texas A&M University, March 26 and April 16, 2010.
 Residues in Hochschild homology,
Working Algebraic Topology Seminar,
Texas A&M University, April 7 and 14, 2010.
 Cohomology of Hopf algebras,
Short Course,
University of Buenos Aires, Argentina, May 1731, 2010.
 Deformations of crossed products and graded Hecke algebras,
Noncommutative Geometry Seminar,
University of Buenos Aires, Argentina, May 18, 2010.
 Quantum symmetric algebras,
Algebra Seminar,
University of Uruguay, Montevideo, May 20, 2010.
 Cohomology of pointed Hopf algebras,
Student Homological Algebra Seminar,
University of Buenos Aires, Argentina, May 26, 2010.
 Graded Hecke algebras and deformations,
Algebra and Combinatorics Seminar,
Texas A&M University, September 17, 2010.
 Support varieties and representation type,
Algebra and Geometry Seminar,
Stockholm University, Sweden, February 9, 2011.
 Support varieties and representation type,
Algebra and Geometry Seminar,
Uppsala University, Sweden, March 8, 2011.
 Deformations of crossed products and graded Hecke algebras,
Algebra Seminar,
Norwegian University of Science and Technology, Trondheim,
March 23, 2011.
 Koszul algebras,
Groups and Dynamics Working Seminar,
Texas A&M University, November 14, 2012.
 Tensor ideals and varieties for modules,
Noncommutative Algebraic Geometry and Representation Theory Seminar,
MSRI, Berkeley, March 5, 2013.
 Tensor ideals and varieties for modules,
Algebra Seminar,
University of Southern California,
April 22, 2013.
 Hopf algebras and varieties for modules,
Algebra and Discrete Mathematics Seminar,
University of California Davis,
April 24, 2013.
 Lie algebras, quantum groups, and PoincareBirkhoffWitt Theorems,
Graduate Student Algebra and Discrete Mathematics Seminar,
University of California Davis,
April 24, 2013.
 PoincareBirkhoffWitt Theorems,
Algebra Seminar,
Northwestern University,
May 29, 2013.
 Hopf algebras and varieties for modules,
Group Theory Seminar,
University of Chicago,
May 30, 2013.
 PoincareBirkhoffWitt Theorems,
Algebra and Combinatorics Seminar,
Texas A&M University,
October 4, 2013.
 Tensor categories from finite groups,
Hopf Working Seminar,
University of Southern California,
November 1, 2013.
 Representations of finite groups: Cohomology and varieties
for modules, and
Noncommutative representations constructed from finite groups,
Algebra and Algebraic Geometry Preseminar and Seminar,
University of Washington, Seattle, January 7, 2014.
 Hochschild cohomology and algebraic deformation theory,
Noncommutative Geometry Seminar,
Texas A&M University,
February 5, 2014.
 Hopf algebras and varieties for modules,
Algebra and Combinatorics Seminar,
Texas A&M University, February 6, 2015.
 Algebraic deformation theory and Hochschild cohomology, Minitalk,
Graduate Student Organization Seminar, September 24, 2015.
 A tale of two constructions in Hochschild cohomology,
Algebra and Combinatorics Seminar,
Texas A&M University, February 12, 2016.
 What is cohomology?
Junior Algebra and Geometry Seminar,
Texas A&M University, March 1, 2016.
 Hochschild cohomology and varieties for modules,
Homological Methods Seminar,
University of Toronto, November 23, 2016.
 The Lie structure on Hochschild cohomology,
Homological Methods Seminar,
University of Toronto, March 8, 2017.
 Algebraic deformation theory and the structure
of Hochschild cohomology,
Algebra and Combinatorics Seminar,
Texas A&M University, September 29, 2017.
 Lie algebra structure on derivations and Hochschild cohomology,
Algebra and Combinatorics Seminar,
Texas A&M University, September 7, 2018.
 Hopf algebras and the cohomological finite generation conjecture,
Algebra and Combinatorics Seminar,
Texas A&M University, February 8, 2019.
 Symmetry and solvability, Seminar,
Texas A&M University Galveston, January 10, 2020.
 Symmetry and solvability, Undergraduate Math Club,
Zoom talk,
Michigan State University, September 14, 2020.
 Symmetric tensor categories and skew group algebras,
Algebra and Algebraic Geometry PreSeminar,
University of Washington, Seattle, November 7, 2023.
 Support varieties for finite tensor categories,
Algebra and Algebraic Geometry Seminar,
University of Washington, Seattle, November 7, 2023.