School of Mathematics

How to modify the Langlands' dual group

Joseph Bernstein
Tel Aviv University; Member, School of Mathematics
November 20, 2017

Let $\mathcal G$ be a split reductive group over a $p$-adic field $F$, and $G$ the group of its $F$-points.

The main insight of the local Langlands program is that to every irreducible smooth representation $(\rho, G, V )$ should correspond a morphism $\nu_\rho : W_F \to {}^\vee G$ of the Weil group $W_F$ of the field $F$ to the Langlands' dual group $^\vee G$.

Wild harmonic bundles and related topics II

Takuro Mochizuki
Kyoto University
November 17, 2017

Harmonic bundles are flat bundles equipped with a pluri-harmonic metric. They are very useful in the study of flat bundles on complex projective manifolds. Indeed, according to the fundamental theorem of Corlette, any semisimple flat bundle on a projective manifold has a pluri-harmonic metric. Moreover, Simpson generalized many important theorems for polarizable variation of Hodge structures, such as Hard Lefschetz Theorem, to the context of harmonic bundles.

Thin monodromy and Lyapunov exponents, via Hodge theory

Simion Filip
Harvard University
November 15, 2017
I will discuss a connection between monodromy groups of variations of Hodge structure and the global behavior of the associated period map. The large-scale information in the period map is contained in the Lyapunov exponents, which are invariants coming from dynamical systems. In some cases when the monodromy group is thin, i.e. infinite-index in the relevant arithmetic lattice, one can construct new geometric objects that cannot exist in the arithmetic case.

Wild harmonic bundles and related topics I

Takuro Mochizuki
Kyoto University
November 15, 2017

Harmonic bundles are flat bundles equipped with a pluri-harmonic metric. They are very useful in the study of flat bundles on complex projective manifolds. Indeed, according to the fundamental theorem of Corlette, any semisimple flat bundle on a projective manifold has a pluri-harmonic metric. Moreover, Simpson generalized many important theorems for polarizable variation of Hodge structures, such as Hard Lefschetz Theorem, to the context of harmonic bundles.

Learning models: connections between boosting, hard-core distributions, dense models, GAN, and regularity II

Russell Impagliazzo
University of California, San Diego
November 14, 2017

A theme that cuts across many domains of computer science and mathematics is to find simple representations of complex mathematical objects such as graphs, functions, or distributions on data. These representations need to capture how the object interacts with a class of tests, and to approximately determine the outcome of these tests.

Automorphic forms and motivic cohomology I

Akshay Venkatesh
Stanford University; Distinguished Visiting Professor, School of Mathematics
November 14, 2017

In the lectures I will formulate a conjecture asserting that there is a hidden action of certain motivic cohomology groups on the cohomology of arithmetic groups. One can construct this action, tensored with $\mathbb C$, using differential forms. Also one can construct it, tensored with $\mathbb Q_p$, by using a derived version of the Hecke algebra (or a derived version of the Galois deformation rings).

Learning models: connections between boosting, hard-core distributions, dense models, GAN, and regularity I

Russell Impagliazzo
University of California, San Diego
November 13, 2017

A theme that cuts across many domains of computer science and mathematics is to find simple representations of complex mathematical objects such as graphs, functions, or distributions on data. These representations need to capture how the object interacts with a class of tests, and to approximately determine the outcome of these tests.

Decomposition theorem for semisimple algebraic holonomic D-modules

Takuro Mochizuki
Kyoto University
November 13, 2017

Decomposition theorem for perverse sheaves on algebraic varieties, proved by Beilinson-Bernstein-Deligne-Gabber, is one of the most important and useful theorems in the contemporary mathematics. By the Riemann-Hilbert correspondence, we may regard it as a theorem for regular holonomic D-modules of geometric origin. Rather recently, it was generalized to the context of semisimple holonomic D-modules which are not necessarily regular.

Solvable descent for cuspidal automorphic representations of GL(n)'

Laurent Clozel
Universite Paris-Sud; Member, School of Mathematics
November 10, 2017

Abstract: A rather notorious mistake occurs p. 217 in the proof of Lemma 6.3 of the book "Simple algebras, base change, and the advanced theory of the trace formula" (1989) by J. Arthur, L. Clozel.  E. Lapid and J. Rogawski (1998) proposed a proof of this lemma based on what they called "Theorem A".