*20.05.2020*: The Übung on May 20 got derailed by connectivity problems and had to end early, but the complete whiteboard notes (including the portion that was meant to come after we ended the session) are posted below.*21.04.2020*: As decided in the first lecture, the**Wednesday**lectures will take place from**11:00 to 12:30**sharp (i.e. if you come at 11:15, you are late) and the problem class from**13:30 to 15:00**so that we have a full hour for lunch.

The current version of the notes includes Lectures 1-5, Appendices A-C and the bibliography. (last update: 19.05.2020 at 16:50)

*(Note: The file
behind this link will be updated
routinely throughout the semester, so make sure you have pressed the "refresh" button if necessary to get the
most recent update.)*

As this course progresses, I will be revising the lecture notes I produced while teaching a similar
course at UCL four years ago, and making the revision available at the link above.
(The complete unrevised version is available on the arXiv,
in case you're curious.)
The aim will be to cover approximately one "lecture" in the notes every week (hence 2 actual class lectures,
plus Übung),
so you can expect the link to be updated weekly.
These notes are to be published as a book in the *EMS Series of Lectures in Mathematics* series
when they are finished. For that reason and others, I warmly welcome all information about
**typos** or **mathematical errors** you may notice, or any other **suggestions** that occur to you
as you read them. Just send me an e-mail.

I will also post my whiteboard notes from the online lectures here as they become available:

April 21
April 22
April 22 (Übung)
April 28
April 29
April 29 (Übung)
May 5
May 6
May 6 (Übung)
May 12
May 13
May 19
May 20
May 20 (Übung)

**Instructor:** Prof. Chris Wendl (for contact information and office hours see my homepage)

**Moodle**: https://moodle.hu-berlin.de/course/view.php?id=95257

IMPORTANT: You will need to join the moodle for the course in order to obtain the Zoom links for online
lectures. HU students can access moodle using their HU username and password.
Non-HU users can access it by following the above link and then setting up a HU Moodle Account
with their external e-mail address as a username. You will need an enrolment key,
which was announced during the first lecture; if you have not yet joined the moodle but
would still like to attend the class, contact me for the enrolment key.

**Time and place:** Lectures on Tuesdays 13:00-15:00 (c.t.) in room 1.115 (RUD25),
and Wednesdays 11:00-12:30 (s.t.) in room 1-1304 (RUD26), plus
Problem Class (Übung) Wednesdays 13:30-15:00 (s.t.) in room 1.011 (RUD25).

All lectures and problem classes will take place via ZOOM until a return to
campus is possible. The required links for Zoom meetings will be posted on the **moodle** (see above).

**Language:** The course will be taught in English.

**Prerequisites:**
I will assume that all students are comfortable with the essentials of differential geometry
(smooth manifolds, vector fields and Lie bracket, differential forms and Stokes' theorem, de Rham cohomology,
connections on vector bundles),
as well as some basic algebraic topology (fundamental group, singular homology and cohomology)
and functional analysis (continuous linear operators on Banach spaces, the standard *L ^{p}*-spaces).
Some previous knowledge of additional topics from topology (homological intersection theory,
the first Chern class) and functional analysis or PDE theory (Fourier transforms, distributions, Sobolev spaces)
will sometimes be helpful. For students who have not seen any symplectic or contact geometry
before, I will give a concise overview of the subject in the first problem class.
Some prior familiarity with more directly related topics such as
holomorphic curves and Floer homology may be helpful for grasping the big picture, but
will not be explicitly assumed.

**Contents:**

Symplectic manifolds were invented around the turn of the 20th century as the
natural geometric setting in which to study Hamilton's equations of motion
from classical mechanics. The subject of symplectic geometry has developed
considerably since then, and it retains a close connection with theoretical
physics despite being technically a branch of “pure” mathematics. In particular,
the subfield known as symplectic *topology*, which deals with “global”
rather than “local” properties of symplectic manifolds, has witnessed an
explosion of activity since the introduction of techniques from elliptic PDE
theory in the 1980s. The
most spectacular advances came from Gromov's theory of *pseudoholomorphic
curves*, which has led to a wide assortment of algebraic invariants of
symplectic manifolds, some of them related to structures
that physicists study in quantum field theory or string theory.
Symplectic field theory (SFT) is one such invariant, or more accurately,
a large framework for extracting algebraic invariants of contact manifolds
(the odd-dimensional analogue of symplectic manifolds) and symplectic cobordisms
between them by counting punctured holomorphic curves.

After a brief introduction and survey of the structure of SFT, the goal of this course will be to establish the basic analytical underpinnings of the theory (moduli spaces, Fredholm theory, index calculation, transversality and compactness), and then explore a few of its applications to natural questions in contact geometry such as distinguishing non-diffeomorphic contact structures, obstructing symplectic fillings of contact manifolds, and proving the existence of periodic orbits of Hamiltonian systems on contact-type hypersurfaces (AKA the “Weinstein conjecture”).

As some students may already have heard, giving a fully rigorous definition of SFT requires very recent and subtle analytical ideas (e.g. polyfolds) which would fill an entire course in themselves, thus we will not attempt this, but instead focus on the “classical” portion of the theory (i.e. everything that can be proved without needing multiply covered holomorphic curves to be regular). This is sufficient for the applications mentioned above.

**References:**
The course will mostly follow my lecture notes which are posted (with regular updates)
at the top of this page.

If you are new to symplectic geometry, you will find most of the basics explained
nicely in the book Lectures
on Symplectic Geometry by Ana Cannas da Silva (Springer LNM, 2008).
If at some point you decide to get really serious about symplectic topology
and/or holomorphic curve theory, then you'll eventually also need to buy
both of the books by Dusa McDuff and Dietmar Salamon:

- Introduction to Symplectic Topology (3rd edition, Oxford University Press, 2017)
- J-holomorphic Curves and Symplectic Topology (2nd edition, AMS, 2012)

**Homework:**
I will assign exercises sometimes. Sometimes I will discuss them in the
problem class. They will not be graded.

**Grades:**
Since this is an advanced course, I have a fairly relaxed attitude about
grades. If you stay with me for the whole semester, you can come to my office /
meet with me on Zoom for a conversation (let's pretend that's the English translation of
“mündliche Prüfung”). The format is as follows:
you pick one particular topic from the course to focus on (typically the contents
of one week, i.e. one lecture in the notes), and we will talk about that.
If you demonstrate that you learned something
interesting from the course, you'll get a good grade.