Georgia Institute of Technology College of Sciences

The Grothendieck group K_0 of a commutative ring is well-known to be a \lambda-ring: although the exterior powers are non-additive, they induce maps on K_0 satisfying various universal identities. The \lambda-operations are known to give homomorphisms on higher K-groups. In joint work in progress with Barwick, Glasman, and Nikolaus, we give a general framework for such operations. Namely, we show that the K-theory space is naturally functorial with respect to polynomial functors, and describe a universal property of the extended K-theory functor.

We are going to discuss one of the open problems of geometric tomography about projections. Along with partial previous results, the proof of the problem below will be investigated.Let $2\le k\le d-1$ and let $P$ and $Q$ be two convex polytopes in ${\mathbb E^d}$. Assume that their projections, $P|H$, $Q|H$, onto every $k$-dimensional subspace $H$, are congruent. We will show that $P$ and $Q$ or $P$ and $-Q$ are translates of each other.

We will review the definition of the Chekanov-Eliashberg differentialgraded algebra for Legendrian knots in R^3 and look at examples tounderstand a few of the invariants that come from Legendrian contacthomology.

Khovanov homology is a powerful and computable homology theory for links which extends to tangles and tangle cobordisms. It is closely, but perhaps mysteriously, related to many flavors of Floer homology. Szabó has constructed a combinatorial spectral sequence from Khovanov homology which (conjecturally) converges to a Heegaard Floer-theoretic object. We will discuss work in progress to extend Szabó’s construction to an invariant of tangles and surfaces in the four-sphere.

We will review the definition of the Chekanov-Eliashberg differentialgraded algebra for Legendrian knots in R^3 and look at examples tounderstand a few of the invariants that come from Legendrian contacthomology.

Quantum topology is a collection of ideas and techniques for studying knots and manifolds using ideas coming from quantum mechanics and quantum field theory. We present a gentle introduction to this topic via Kauffman bracket skein algebras of surfaces, an algebraic object that relates "quantum information" about knots embedded in the surface to the representation theory of the fundamental group of the surface. In general, skein algebras are difficult to compute. We associate to every triangulation of the

I will give 2 or 3 lectures on Legendrian contact homology. This invariant has played a big role in our understanding of Legendrian submanifolds of contact manifolds in all dimensions. We will discuss the general definition but focus on the 3-dimensional setting where it easiest to compute (and describe Legendrian knots). I will also discuss the A^\infty structure associated to the linearized co-chain groups of contact homology.

I will give 2 or 3 lectures on Legendrian contact homology. This invariant has played a big role in our understanding of Legendrian submanifolds of contact manifolds in all dimensions. We will discuss the general definition but focus on the 3-dimensional setting where it easiest to compute (and describe Legendrian knots). I will also discuss the A^\infty structure associated to the linearized co-chain groups of contact homology.

We will discuss some facts about intersection forms on closed, oriented 4-manifolds. We will also sketch the proof that for two closed, oriented, simply connected manifolds, they are homotopy equivalent if and only if they have isomorphic intersection forms.

Trisections of 4-manifolds relative to their boundary were introduced by Gay and Kirby in 2012. They are decompositions of 4-manifolds that induce open book decomposition in the bounding 3-manifolds. This talk will focus on diagrams of relative trisections and will be divided in two. In the first half I will focus on trisections as fillings of open book decompositions and I will present different fillings of different open book decompositions of the Poincare homology sphere.