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Connections between tau functions and the Kontsevich matrix integral, Part II

Nathan Hayford

4:00pm-5:00pm

CMC 130

**Title**

**Speaker**

**Time**

**Place**

Connections between tau functions and the Kontsevich matrix integral

Nathan Hayford

4:00pm-5:00pm

CMC 130

**Abstract**

It has been known since the 90’s that the tau function for the KdV hierarchy is equivalent to the partition function for a certain matrix model. Because of the broad scope of problems random matrix theory is capable of addressing (2D quantum gravity, combinatorics, quantum computing, etc.), results of this form are particularly relevant, in that they provide an analytic tool for computing matrix integrals.

By way of example, I will attempt to explain what a tau function is and why knowledge of it is useful; the example shall come from the theory of linear ordinary differential equations with Fuchsian singularities. I will also attempt to establish (or at least sketch) the connection of such a tau function to the Kontsevich matrix integral, first introduced in [1]. Finally, if time permits, I’d like to try and sell the utility of this result by providing a few explicit examples of where this matrix integral has made an impact.

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Regularity results for weak solutions of \(p\)-Laplacian-type equations, Part II

Diego Ricciotti

4:00pm-5:00pm

CMC 130

**Title**

**Speaker**

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Regularity results for weak solutions of \(p\)-Laplacian-type equations

Diego Ricciotti

4:00pm-5:00pm

CMC 130

**Abstract**

Minimizing integral functionals of the calculus of variations with \(p\)-growth in Sobolev spaces leads to consider weak solutions to equations of \(p\)-Laplacian type. A focal point of the theory is then to investigate additional regularity properties possessed by such solutions. In this regard, after presenting an overview of results and techniques developed for the \(p\)-Laplace equation, I will discuss some recent advances pertaining ‘anisotropic’ \(p\)-Laplacian-type equations.

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Some theorem(s) from the spectral theory of Sturm–Lioulille operator, Part III

E. A. Rakhmanov

4:00pm-5:00pm

CMC 130

**Title**

**Speaker**

**Time**

**Place**

Some theorem(s) from the spectral theory of Sturm–Lioulille operator, Part II

E. A. Rakhmanov

4:00pm-5:00pm

CMC 130

**Title**

**Speaker**

**Time**

**Place**

Some theorem(s) from the spectral theory of Sturm–Lioulille operator

E. A. Rakhmanov

4:00pm-5:00pm

CMC 130

**Abstract**

We will discuss (mainly discrete) Sturm-Lioulille operators, however most part of basic theorems are similar. One of the most interesting recent advances is a C. Remling theorem a.k.a Breimesser–Pearson theorem, a.k.a Denisov–Rakhmanov–Remling theorem. Loosely speaking, the theorem says that if the potential of an operator is obtained by certain limiting process, then its spectral measure is reflectionless. The “mess” in the names shows that there are, at least, several connections (versions).

I will try to explain some of them.

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Some thoughts on uniform approximation by polyanalytic functions, Part II

Dima Khavinson

4:00pm-5:00pm

CMC 130

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Some thoughts on uniform approximation by polyanalytic functions, Part I

Dima Khavinson

4:00pm-5:00pm

CMC 108

**Abstract**

We shall discuss the problem of uniform approximation of continuous functions on a compact subset \(K\) of the plane by the so-called rational modules, consisting of functions \(f\) satisfying \((d/dz*)^n f=0\), \(n\geq 1\), near \(K\). (For \(n=1\), this is a well-known old problem of approximation by rational functions with poles off \(K\). For \(n=2\), the approximants already do not form an algebra, but a module of dimension 2 over \(R(K)\) with the basis \(1,z*\), where \(*\) denotes complex conjugation.) The main idea is to extend the concept of analytic content introduced by DK in '82 for rational approximation to this new situation and reduce the problem to approximating just one particular function.

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Optimal polynomial approximants and simultaneous zero-free approximation

Myrto Manolaki

4:00pm-5:00pm

CMC 108

**Abstract**

Given a Hilbert space \(H\) of analytic functions on the unit disc and a function \(f \in H\), a polynomial \(p_n\) is called an optimal polynomial approximant of degree \(n\) of \(1/f\) if \(p_n\) minimizes the norm of \(pf-1\) over all polynomials \(p\) of degree at most \(n\). Optimal polynomial approximants arise naturally in the study of cyclicity in Dirichlet-type spaces. In this talk, we will focus on the boundary behavior of such approximants in the Hardy space \(H^2\), and we will discuss an auxiliary result on simultaneous zero-free approximation, which is of independent interest. (Joint work with Catherine Bénéteau, Oleg Ivrii and Daniel Seco.)

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Theorems and problem in harmonic mappings

Daoud Bshouty

Technion — Israel Institute of Technology

Haifa, Israel

4:00pm-5:00pm

CMC 108

**Abstract**

Since de Branges’s proof of the Bieberbach conjecture many complex analysts were driven towards the study of univalent harmonic mappings due to the analogy of this field to univalent analytic functions as presented by Clunie and Sheil-Small in their 1984 paper. For the past 30 years several directions were explored via complex analytic methods. I shall present a few of these techniques, theorems and problems in four topics: zeroes of harmonic polynomials, existence and uniqueness of the Riemann mapping theorem, univalent harmonic mappings with finite Blaschke dilatations, and boundary behavior of univalent harmonic mappings.