A head-shot of me near the southern Oregon coast

Theo Johnson-Freyd

NSF Postdoctoral Fellow and Boas Assistant Professor,
Department of Mathematics, Northwestern University

e-mail: theojf at math dot northwestern dot edu
Office: 312 Lunt Hall, Northwestern University, Evanston, IL, 60202

Brief bio

My primary research is in an area I would call "topological physics": a mathematical physicist, I focus on quantum field theory, topological field theory, perturbative quantization, category theory, representation theory, and algebraic topology. A more detailed description of my current research interests and projects my be found by reading my recent grant applications. For even more details, see my publications and seminar presentations. Of course, if you want fewer details, perhaps you want my Curriculum Vitae (PDF).

I received my PhD from UC Berkeley in 2013, under the supervision of Nicolai Reshetikhin. As an NSF postdoc, my sponsoring scientist at Northwestern in Kevin Costello. Other collaborators include Alex Chirvasitu, Owen Gwilliam, Dan Berwick-Evans, and Claudia Scheimbauer.



My publications and submitted-for-publication preprints are listed below. Some not-for-publication preprints are listed under other documents.

Other documents


I have an unfinited draft of a textbook on Lie theory, based on lectures given at UC Berkeley in 2006–08:

Chapters 1–6 of the full volume are almost exactly the same as the edited notes from M. Haiman (2008), but there have been some formatting changes. Chapter 7 is based mostly on lectures 20–31 of Anton's notes from the 2006 Tag Team Lie Groups course (PDF). Chapter 8 is drawn from V. Serganova (2010). The first chapter of Part II: Quantum Groups has now been incorporated. Ultimately Part II will consist of between five and six chapters, based on the lectures by N. Reshetikhin (2009) and V. Serganova (2010).

Not-for-publication preprints

The following preprints may be of interest, but are not destined for publication.

Class Notes

I occasionally "Live-TeX" notes from classes and lectures. As with any notes, mine are replete with omissions and errors, undoubtedly; typing does allow me to catch questions from the audience and jokes from the professors, so these are included as well. Needless to say, anything good about the notes, and in particular presentation of the mathematical material, is due to the professor of the class. Anything bad about them, and in particular every inaccuracy, is mine. Use them with care. Also, please e-mail me with corrections: typos are trivial to fix, and mathematical errors should not be allowed to propagate. I was inspired to start typing lecture notes after watching Anton Geraschenko do it, and appreciate his advice.

Please note that the TAR.GZ files include TeX sources and plenty of other detritus: auxiliary files, partly completed problem sets, etc. You are welcome to download them, but I make no promises that the files will load on your computer: that will depend on whether your TeX installation exactly matches mine.

Grant and job application materials

Linked below are the application materials I produced in Fall of 2012 for my postdoc search (which was relatively successful). If you are a PhD student applying to postdocs, be sure to look over applications other than mine — I have very little data on what parts of my applications helped me, and what parts hurt (although nothing hurt so much as to keep me from winning a postdoc). In fact, I recommend looking more widely than just the Secret Blogging Seminar crowd, as theirs are the applications I read before writing mine, and perhaps we've just been propagating the same mistakes.


As many graduate students discover when taking their language exams, you don't need any training in French in order to read Mathematical French. (It helps that Mathematical English is more French-inflected than is Colloquial English.) As evidence, I have translated into English Deligne's article Catégories Tensorielles (French original).

One of my more satisfying activities is that I am a reviewer for MathReviews. Of my reviews, two appeared in the September 2012 print addition: MR2742432 (2012i:55005): Stolz and Teichner, Supersymmetric field theories and generalized cohomology, 2011 and MR2752518 (2012i:81001): Baez and Lauda, A prehistory of n-categorical physics, 2011.

Early in graduate school, I wrote up a short survey of Lie bialgebras: Poisson Lie linear algebra in the graphical language (TeX source).

If you are curious, you can read the syllabus for my PhD Candidacy Qualifying Exam (UC Berkeley, 11 June 2009).

Seminar presentations

Some talks I have given (or will give) are listed below. You can open all abstracts or close all abstracts if you like.











I have taught the following classes at Northwestern:

I have taught the following classes at UC Berkeley:

I have also given short classes at Canada/USA Mathcamp.


My husband and I are avid cooks. For a while we collected recipes and discussions at Local Seasoning. We are on hiatus right now, but may start up again.

In a previous life, I was a kitchen manager at Columbae House, at Stanford University. Around the same time, I was also a dancer, and I choreographed the Opening Committee performance for the 2007 Stanford Viennese Ball (video).

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