# PATCH Day at Temple

February 26, 2016

## Schedule of Talks

Morning (background) lectures will take place in Wachman 527.
Afternoon lectures will take place in Wachman 617.

- 10:00 AM:
**Josh
Greene**, Boston College, *Alternating links and the Tait conjectures*.
- 11:30 AM:
**Lenny Ng**, Duke
University, *Using cotangent bundles and symplectic geometry to define knot invariants*.

- 12:30 PM: Lunch.

- 3:00 PM:
**Lenny Ng**, Duke
University, *Knot contact homology and string topology*.
- 4:30 PM:
**Josh
Greene**, Boston College, *Alternating links and definite surfaces*.

## Abstracts

Josh Greene,

*Alternating links and the Tait conjectures*
ABSTRACT:
I will present some background on the classical Tait conjectures for
alternating links.

Josh Greene, *Alternating links and definite surfaces*

ABSTRACT:
I will describe a characterization of alternating links in terms intrinsic to
the link exterior and use it to derive some properties of these links,
including algorithmic detection and new proofs of some of Tait's conjectures.

Lenny Ng, *Using cotangent bundles and symplectic geometry to define knot invariants*

ABSTRACT:
Symplectic geometry has recently emerged as a key tool in the study of
low-dimensional topology. One approach, championed by Arnol'd, is to examine
the topology of a smooth manifold through the symplectic geometry of its
cotangent bundle, building on the familiar concept of phase space from
classical mechanics. I'll describe a way to use this approach, combined with
the modern theory of Legendrian contact homology (which I'll also introduce),
to construct a rather powerful invariant of knots called "knot contact homology".

Lenny Ng, *Knot contact homology and string topology*

ABSTRACT:
Although knot contact homology has its origins in symplectic geometry and
holomorphic curves, it has a surprising relation to a more classical knot
invariant, the fundamental group of the knot complement. I'll discuss how one
can use string topology to make this relation a bit less surprising (in joint
work with Kai Cieliebak, Tobias Ekholm, and Janko Latschev), and apply this to
show that knot contact homology characterizes various types of knots.

## Sponsors