Anatoly Vershik, St. Petersburg Department of Steklov Institute of Mathematics
"Standard and non-standard filtrations and tensor-like products of algebras (NOTE: JOINT LIE GROUP/LOGIC SEMINAR!!)"
Time: 12:00 PM
Location: Hill 705
Abstract: the problem of the classification of the decreasing sequences of algebras (or sigma-fileds) leads to the fundmental
notion of standardness. The main partial case is classification of dyadic filtrations or classification of infinite tensor-like
product of algebras $M_2(C)$. The tool of classifiction is criteria of standardness; the invariants in general case
is "highest Kolmogorov 0-1 laws" which tell us about behavior of filtrations in infinity".
Past Talks
Friday, April 21st
Haijun Tan , Changchun University of Science and Technology and Rutgers University
"Some non-graded modules for the Virasoro algebra and affine Lie algebras"
Time: 12:00 PM
Location: Hill 705
Abstract: In this talk, we will introduce several classes of non-graded modules for the Virasoro algebra and affine Lie algebras.
Non-graded modules include some restricted modules, which are in some sense the most important modules for
the representation theory of vertex algebras, and non-restricted modules.
We will describe the structures and the irreducible conditions of these modules constructed by us.
Friday, April 14th
Stephen Griffeth, Universidad de Talca, Chile
"The support of the spherical representation of the rational Cherednik algebra of a complex reflection group"
Time: 12:00 PM
Location: Hill 705
Abstract: The Dunkl operators are differential operators on polynomials that deform the ordinary partial derivatives and depend upon a choice of complex reflection group W and a deformation parameter c. We describe how to calculate, for all choices of W and c, the zero set of the largest proper ideal of polynomials stable by the Dunkl operators in two ways: first, in terms of a certain special function deforming the usual exponential function, and second, in terms of Schur elements for finite Hecke algebras. Special cases of this result have been previously obtained using different techniques by Dunkl-Opdam, Etingof, and Varagnolo-Vasserot.
Friday, April 7th
Yi Sun, Columbia University
"Affine Macdonald conjectures and special values of Felder-Varchenko functions"
Time: 12:00 PM
Location: Hill 705
Abstract: I will explain how to refine the statement of the denominator and evaluation conjectures for affine Macdonald polynomials proposed by Etingof-Kirillov Jr. and to prove the first non-trivial cases of these conjectures. Our method applies recent work of the speaker to relate these conjectures for U_q(sl_2 hat) to evaluations of certain theta hypergeometric integrals defined by Felder-Varchenko. We then evaluate the resulting integrals, which may be of independent interest, by well-chosen applications of the elliptic beta integral of Spiridonov.
These results are joint work with E. Rains and A. Varchenko.
Friday, March 31st
Yi-Zhi Huang, Rutgers University
"Intertwining operators among twisted modules associated to not-necessarily-commutative automorphisms"
Time: 12:00 PM
Location: Hill 705
Abstract:
Intertwining operators among twisted modules or twisted intertwining operators for a vertex operator algebra are the main objects of interest in the construction and study of orbifold conformal field theories. However, there has not been even a definition of such operators among twisted modules associated to noncommutative automorphisms in the literature. In a recent paper (arXiv:1702.05845), I have introduced such intertwining operators and have proved their basic properties that are necessary for a future proof of a conjecture and a construction of the associated crossed tensor categories. The proofs of these results involve careful analysis of the analytic extensions corresponding to the actions of the not-necessarily-commutative automorphisms of the vertex operator algebra. In this talk, I will discuss these operators and their properties.
Archive paper arXiv:1702.05845.
Friday, March 10th
Eveliina Peltola, University of Geneva
"Hidden quantum group structure on solution spaces of BPZ PDEs of CFT"
Time: 12:00 PM
Location: Hill 705
Abstract: I describe a systematic method for solving PDEs of conformal field theory, known as Belavin-Polyakov-Zamolodchikov (BPZ) equations. These PDEs also arise in connections with statistical physics, in the theory of Schramm-Loewner evolutions (SLEs). Our method is a correspondence associating vectors in a tensor product representation of a quantum group to Coulomb gas type integral functions, in which properties of the functions are encoded in natural, representation theoretical properties of the vectors. In particular, this hidden quantum group structure on the solution space of such PDEs enables explicit calculation of the asymptotics and monodromy properties of the solutions. This also leads us to a generalization of the Temperley-Lieb algebra, defined in terms of a diagrammatic representation, which is nothing but the commutant algebra of the quantum group in the setup of the quantum Schur-Weyl duality.
Joint work with Kalle Kytölä (Aalto University) and Steven Flores (University of Helsinki).
Friday, March 3rd
You Qi, Yale University
"Categorification at prime roots of unity"
Time: 12:00 PM
Location: Hill 705
Abstract: We sketch an algebraic approach to categorification of quantum groups at a prime root of unity, with the outlook towards eventually categorifying Witten-Reshetikhin-Turaev 3-manifold invariants.
This is based on joint work of the speaker with B. Elias, M. Khovanov and J. Sussan.
Friday, February 24th
Dmitry Vaintrob, IAS
"Mirror symmetry and the K theory of p-adic groups"
Time: 12:00 PM
Location: Hill 705
Abstract:
We study the category of (complex-valued)
finitely-generated smooth representations of a p-adic
group G and its K theory. We show that every representation
has a resolution by representations induced from
finitely-generated representations of open compact
subgroups. We do this by studying another category,
the compactified representation category recently defined
by Bezrukavnikov and Kazhdan, and using techniques from
toric mirror symmetry to send it functorially into a geometric
category of equivariant constructible sheaves on the
Bruhat-Tits building.
Friday, February 17th
Siddhartha Sahi, Rutgers University
"Schur Q-functions and the Capelli eigenvalue problem for the Lie superalgebra q(n)"
Time: 12:00 PM
Location: Hill 705
Abstract: Let V be the associative superalgebra of type Q(n). Then V carries a two sided action of the queer Lie superalgebra q(n) and hence an action of l:= q(n)× q(n). We consider a distinguished basis {D_λ} of the algebra of l-invariant polynomial super-differential operators on V, which is indexed by strict partitions of length at most n. We show that the spectrum of D_λ, on the algebra P(V) of super-polynomials on V, is given by the factorial Schur Q-function of Okounkov and Ivanov.
This generalizes a result of Nazarov. As a further application we show that the radial projections of the spherical polynomials of the symmetric pair (q(n) x q(n),q(n)) are the classical Schur Q-functions.
This is joint work with Alexander Alldridge and Hadi Salmasian and available at https://arxiv.org/abs/1701.03401
Friday, February 10th
Wilfried Schmid, Harvard University
"B-functions and Hodge Modules"
Time: 12:00 PM
Location: Hill 705
Abstract: After describing how b-functions come up in analysis and geometry, I shall discuss a class of examples that arose in my joint work with Kari Vilonen on unitary representation of reductive groups.
Friday, February 3rd
Robert Laugwitz, Rutgers University
"The Relative Hopf and Drinfeld center of a Monoidal Category"
Time: 12:00 PM
Location: Hill 705
Abstract: The Drinfeld (or quantum) center of a monoidal category is a well-known categorical construction with applications to quantum field theory. From the point of view of representation theory, this construction gives the Drinfeld double of a Hopf algebra. Another related construction is the Heisenberg double of a Hopf algebra, giving the Weyl algebra as an example. In this talk, I will discuss how these constructions can be adapted to the setting of a monoidal category relative to a braided monoidal category. In this generality, the double bosonization of S. Majid is recovered on the algebraic level, and a purely categorical definition of a generalization of the Heisenberg double can be given, called the relative Hopf center. Further, generalizing work of V. Ostrik, a Morita dual of the relative Drinfeld center can be identified, giving a classification of categorical modules in the case of a finite tensor category. The relative Hopf center obtains a categorical action of the Drinfeld center this way, generalizing a result of J.-H. Lu.
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