Quantum topology and categorified representation theory
Monday 26th June 2017 to Friday 30th June 2017
09:00 to 09:50  Registration  
09:50 to 10:00  Welcome from Christie Marr (INI Deputy Director)  
10:00 to 11:00 
Christian Blanchet (Université Denis Diderot) Non semisimple TQFTs from quantum sl(2)
We will describe quantum invariants and TQFTs extracted from quantum sl(2) at root of unity, focusing on new features related with the non semisimplicity of the quantum group at root of 1.

INI 1  
11:00 to 11:30  Morning Coffee  
11:30 to 12:30 
Zsuzsanna Dancso (University of Sydney) Lattices and Homological Algebra
Coauthor: Anthony Licata (Australian National University) I'll begin with some dreams and motivation regarding lifting notions of lattice theory to homological algebra. For most of the talk, we'll study a concrete example: the lattices of integer cuts and flows associated to a finite graph. Given a graph G and choice of spanning tree T, we construct an algebra A(G,T) such that the Groethendieck group of the category of finitely generated A(G,T)modules with the Euler (Ext) pairing contains the cut and flow lattices of G as orthogonal complements. We'll discus many open problems regarding generalisations and possible uses for the extra structure that is present at the category level, such as gradings. Joint work in progress with Anthony Licata.Navigation: 
INI 1  
12:30 to 13:30  Lunch @ Wolfson Court  
13:30 to 14:30 
Peter Samuelson (University of Edinburgh) Hall algebras and Fukaya categories
(joint with Ben Cooper) The multiplication in the Hall algebra of an abelian category is defined by "counting extensions of objects," and the representation theory of this algebra tends to be quite interesting (e.g. Ringel showed the Hall algebra of modules over a quiver is the quantum group). Recently, Burban and Schiffmann explicitly described the Hall algebra of coherent sheaves over an elliptic curve, and various authors have connected this algebra to symmetric functions, Hilbert schemes, torus knot homology, the Heisenberg category, and the skein algebra of the torus. Motivated by this last connection and homological mirror symmetry, we discuss some computations in progress involving the Hall algebra of the Fukaya category of a (topological) surface. 
INI 1  
14:30 to 15:30 
David Rose (University of North Carolina) Traces, current algebras, and link homologies
We'll show how categorical traces and foam categories can be used to define an invariant of braid conjugacy, which can be viewed as a "universal" typeA braid invariant. Applying various functors, we recover several known link homology theories, both for links in the solid torus, and, moresurprisingly, for links in the 3sphere. Variations on this theme produce new annular invariants, and, conjecturally, a homology theory for links in the 3sphere which categorifies the sl(n) link polynomial but is distinct from the KhovanovRozansky theory. Lurking in the background of this story is a family of current algebra representations. This is joint work with Queffelec and Sartori. 
INI 1  
15:30 to 16:00  Afternoon Tea  
16:00 to 17:00 
Hoel Queffelec (CNRS (Centre national de la recherche scientifique)); (Université de Montpellier) Around Chebyshev's polynomial and the skein algebra of the torus
The diagrammatic version of the Jones polynomial, based on the Kauffman bracket skein module, extends to knots in any 3manifold. In the case of thickened surfaces, it can be endowed with the structure of an algebra by stacking. The case of the torus is of particular interest, and C. Frohman and R. Gelca exhibited in 1998 a basis of the skein module for which the multiplication is governed by the particularly simple "producttosum" formula. I'll present a diagrammatic proof of this formula that highlights the role of the Chebyshev's polynomials, before turning to categorification perspectives and their interactions with representation theory. Joint work with H. Russell, D. Rose and P. Wedrich. 
INI 1  
17:00 to 18:00  Welcome Wine Reception at INI 
10:00 to 11:00 
Mikhail Khovanov (Columbia University) How to categorify the ring of integers localized at two
We construct a triangulated monoidal idempotent complete category with the Grothendieck ring naturally isomorphic to the ring of integers with two inverted. This is a joint work with Yin Tian. 
INI 1  
11:00 to 11:30  Morning Coffee  
11:30 to 12:30 
Vanessa Miemietz (University of East Anglia) Introduction to pdg 2representation theory
I will report on joint work with Robert Laugwitz developing an abstract 2representation theory for pdg 2categories, in the spirit of categorification of quantum groups at prime roots of unity by Khovanov, Qi and Elias. 
INI 1  
12:30 to 13:30  Lunch @ Wolfson Court  
13:30 to 14:30 
Lukas Lewark (Universität Bern) An Upsilonlike invariant from KhovanovRozansky homology
Coauthor: Andrew Lobb (Durham University) KhovanovRozansky homology in its most general form (socalled equivariant homology) associates to a knot a chain complex (invariant up to homotopy equivalence) over a certain polynomial ring. Equivariant homology yields various lower bounds to the slice genus, some of them concordance homomorphisms, some not; and also a piecewise linear function which has much resemblance with the recently introduced Upsiloninvariant from HeegaardFloer homology. 
INI 1  
14:30 to 15:30 
Ben Webster (University of Virginia) Representation theory and the Coulomb branch
For many years, my collaborators and I tried to understand the Coulomb branches of certain field theories from physics and failed miserably. Luckily, recent work of BravermanFinkelbergNakajima gives a mathematical construction of these spaces, and algebras quantizing them. I'll discuss an approach to the representation theory of these algebras (building on joint work with BradenLicataProudfoot and many other authors). Applications include a version of the Koszul duality between the Higgs and Coulomb branches of such a theory, a new perspective on category O for Cherednik algebras, and a new understanding of coherent sheaves on Coulomb branches in terms of KLR algebras. Related Links

INI 1  
15:30 to 16:00  Afternoon Tea  
16:00 to 17:00 
Paul Wedrich (Imperial College London) On colored link homologies
I will talk about recent progress in understanding the structure of type A link homologies. This includes the definition of integral, equivariant, colored sl(N) KhovanovRozansky link homologies, which are functorial under link cobordisms, a study of their deformations and stability properties and the question of how these invariants extend to links in thickened surfaces. Joint work with M. Ehrig, H. Queffelec, D. Rose and D. Tubbenhauer. 
INI 1 
10:00 to 11:00 
Andrei Negut (Massachusetts Institute of Technology) Categorified knot invariants and algebraic geometry
In this talk, we will survey some recent progress in a broad and developing framework that seeks to connect categorified knot invariants, geometric representation theory, Hilbert schemes and matrix factorizations. The contributions discussed come from the work of many mathematicians, and I hope to also convey some interesting future perspectives on the topic.

INI 1  
11:00 to 11:30  Morning Coffee  
11:30 to 12:30 
Matthew Hogancamp (University of Southern California) Categorical diagonalization
It goes without saying that diagonalization is an important tool in linear algebra and representation theory. In this talk I will discuss joint work with Ben Elias in which we develop a theory of diagonalization of functors, which has relevance both to higher representation theory and to categorified quantum invariants. For most of the talk I will use small examples to illustrate of components of the theory, as well as subtleties which are not visible on the linear algebra level. I will also state our Diagonalization Theorem which, informally, asserts that an object in a monoidal category is diagonalizable if it has enough ``eigenmaps''. Time allowing, I will also mention our main application, which is a diagonalization of the fulltwist Rouquier complexes acting on Soergel bimodules in type A. The resulting categorical eigenprojections categorify qdeformed Young idempotents in Hecke algebras, and are also important for constructing colored link homology theories which, conjecturally, are functorial under 4d cobordisms.

INI 1  
12:30 to 13:30  Lunch @ Wolfson Court  
13:30 to 17:00  Free Afternoon  
19:30 to 22:00  Formal Dinner at Christ's College 
10:00 to 11:00 
Pedro Vaz (Université Catholique de Louvain) 2Verma modules and the KhovanovRozansky link homologies
In this talk I will describe a construction of Khovanov and Rozansky's HOMFLYPT and sl(N)link homologies using a categorification of certain parabolic Verma modules for gl(2k), the latter based on a generalization of KhovanovLaudaRouquier algebras.I will also explain how to prove a conjecture about the spectral sequence from the HOMFLYPTlink homology to the sl(N)link homology (due to Dunfield, Gukov and Rasmussen) using our version of these link homologies.This is joint work with G. Naisse.

INI 1  
11:00 to 11:30  Morning Coffee  
11:30 to 12:30 
Radmila Sazdanovic (North Carolina State University) Nonmultiplicative TQFTs and diagrammatic categorifications of the polynomial ring
Coauthor: Mikhail Khovanov (Columbia University) We focus on nonmultiplicative TQFTs via representations of nonunital rings built out of cobordism categories modulo various relations. Examples include diagrammatic categorifications of the polynomial ring Z[x] and several classes of orthogonal polynomials. 
INI 1  
12:30 to 13:30  Lunch @ Wolfson Court  
13:30 to 14:30 
Daniel Tubbenhauer (Universität Bonn) Some webs and qHowe dualities in types BCD
Coauthor: Antonio Sartori (University of Freiburg) In seminal work, CautisKamnitzerMorrison gave a diagrammatic presentation, via a socalled web calculus, of the category of quantum gln modules tensor generated by the exterior powers. Their novel observation was that a classical tool from representation and invariant theory, known as skew Howe duality, can be quantized and used to construct the corresponding diagrammatic presentation. The work of CautisKamnitzerMorrison was then extended to various other instance (and even categorified), but all of these have in common that they stay in type A. In this talk I will describe the first steps towards generalizing CautisKamnitzerMorrison's results to other types, where several new features (or flaws?) appear. 
INI 1  
14:30 to 15:30 
Yian Tian (Tsinghua University) Towards a categorical bosonfermion correspondence
The celebrated bosonfermion correspondence is an isomorphism between the bosonic Fock space and the fermionic Fock space. We present categorification of the bosonic Fock space and the Heisenberg algebra which is a modification of Khovanov's Heisenberg category. The categorifcation of the fermionic Fock space is based on Honda's category studying contact topology in dimension three. This is a joint work with Mikhail Khovanov.

INI 1  
15:30 to 16:00  Afternoon Tea  
16:00 to 17:00 
Anna Beliakova (Universität Zürich) Quantum Annular Link Homology via Trace Functor
In this talk I will construct a new triply graded invariant of links in a solid torus, which is functorial with respect to annular link cobordisms and admits a quantum sl(2) action. We discuss several properties of this invariant. This is a joint work with Kris Putyra and Stephan Wehrli. 
INI 1 
11:00 to 11:30  Morning Coffee  
12:30 to 13:30  Lunch @ Wolfson Court  
15:00 to 16:00 
Cameron Gordon (University of Texas at Austin) Leftorderability and 3manifold groups: Rothschild Lecture
The fundamental group is a more or less complete
invariant of a 3dimensional manifold. We will discuss how the purely algebraic
question of whether or not this group has a leftinvariant total order appears
to be related to two other, seemingly quite different, properties of the
manifold, one geometric and the other essentially analytic.

INI 1 