Theo Johnson-Freyd
Contact info:
e-mail: theojf at math dot this university dot edu
Office Hours: Tuesdays 10am-11am and Thursdays 1pm-2pm in
844 Evans, or e-mail for other times.
Contents
Current Teaching
This semester I am a GSI for two sections of Math 53 with Prof. John
Neu: my sections are #107 from 12:10 to 1:00 on Mondays, Wednesdays, and
Fridays, and #106 from 3:10 to 4:00 those same days. There is no general
course webpage; this space
will be used for things specific to my sections (for enrollment
questions, see the Head GSI's webpage here). In
particular,
I will post quizzes and worksheets handed out in class. Quizzes,
worksheets, and answer keys are all PDFs. If you are on a Mac, these
should open automatically; Windows users may need to download Adobe Reader if it is
not already installed.
Worksheets
Quizes
Other Handouts
Previous Teaching
C*-Algebras
In Spring 2008, I was enrolled in Marc Rieffel's class on C* algebras.
I have been TeXing notes for that class, mostly for my own benefit, but
there have been requests that I make such notes available online. The
most recent copy of the pdf is available here (about 600 KB). If for whatever reason
you want to read the raw TeX source, all my files for the class are
available as a tarball here (includes
out-of-date PDFs; about 4 MB). These files were last updated
Monday, 12-May-2008 18:15:05 UTC.
Other things to read
- Divergent Series. Talk given 18
October 2007 at Many Cheerful Facts, a weekly graduate-student talk series
with more-or-less introductory talks. Abstract: "Mathematicians through
the ages have varied from terrified of divergent sums to only mildly
scared of them: Euler, most famously, made great use of divergent series,
whereas Abel called them "the invention of the devil". In this talk, I
will survey the most important methods of summing divergent series, and
make general vague remarks about them. I will quote many results, but
will studiously avoid proving anything."
- Enriching Yoneda. Talk given 11 December
2007 at QFT Mini Conference, a student conference concluding a semester
filled with three quantum-field-theory classes. The goal of the talk was
to formulate and prove the Yoneda embedding theorem for categories
enriched over a closed monoidal category.
- The Composition Law for Feynman Diagrams I: discrete-time quantum mechanics and II: how to glue in general. Papers written
over winter break, in early January 2008. These papers are the beginning
of a project suggested by Nicolai Reshetikhin. Ultimately, the goal is to
show that Feynman-style integration by Feynman-diagram expansion satisfies
all the natural algebraic identities expected for normal integration, and
in particular that it satiesfies something like Fubini's theorem. These
papers provide a proof of these identities for nondegenerate bosonic
theories in 0- or 1-dimensional spacetimes. In dimensions 2 and higher,
I need to learn enough renormalization theory to explain the interaction
there; also interesting is BV formalism for how to Feynman-integrate guage
theories.
I occasionally post math and non-math essays on my weblog, The Orange Juice Files.
I am an avid cook. Some recipes and discussions are available here, althought this file is sorely outdated,
and will be going away soon, as I move it to my food blog. You should
read that blog: my food writing is available at Local Seasoning.
