Seminar spring 2024

January 25, 13:00. 

Speaker: Erlend F. Wold

Venue (We meet in the i 7th floor to find a room, it is difficult to find a room that works all semester)

Titlel: Oka complements

Abstract: We will start by giving some basics about Oka manifolds. Then we will give a “simple” proof of a recent breakthrough result by Kusakabe saying that the complement of (polynomially) convex compact sets in C^n, n\geq 2, are Oka manifolds. This is joint work with Franc Forstneric. 

February 1  13:00. 

Venue (Same preocedure)

Speaker: Ole Brevig

Title: Backward shift on Hardy spaces

Abstract: Let $S$ denote the forward shift and $B=S^\ast$ the backward shift on the sequence space $\ell^2$. Due to a celebrated result of Beurling on the invariant subspaces of $S$, it is natural to let $S$ and $B$ act on certain spaces of analytic functions in the unit disc. After a gentle introduction, we discuss the following problem: What is the norm on $B$ on the Hardy spaces $H^p$?

Based on joint work with Kristian Seip.

February 8  13:00. 

Speaker: Mi Hu

Venue (Same preocedure)

Tile: Improvement of Newton's Method

Abstract: I will discuss an improvement of Newton's method which was created by T. T. Truong. The main advantage of his method (Backtracking New Q-Newton's (BNQN) method) is that the boundary of the basins of the roots seems smooth in the numerical experiments. In this talk, I will present mathematically rigorous proof that for holomorphic polynomials of degree two, the basins of the roots have indeed smooth boundaries. 

February 15  13:00. 

Speaker: Erlend F. Wold 

Venue (Same preocedure)

Tile: Oka properties of complements of complements of closed convex sets in C^n.

Abstract:  From recent breakthroughs by Y. Kusakabe much is known about Oka properties of complements of (polynomially) convex compact sets in C^n. In this talk we will give results in the case of non-compact sets. This is joint work with Franc Forstneric. 

February 22  13:00. Winter break 

February 29  13:00. 

Speaker: Erik Løw 

Venue (Same preocedure)

Tile: TBA

Abstract: TBA

March 7  13:00. 

Speaker: TBA

Venue (Same preocedure)

Tile: TBA

Abstract: TBA

March 14  13:00. 

Speaker: Tuyen Truong

Venue (Same preocedure)

Tile:  Image of dominant endomorphisms of affine space

Abstract: Chevalley's theorem says that if f: A^n -> A^n is a dominant algebraic map, then A^n\f(A^n) is a constructible set. Can we say more, for example which closed algebraic subvariety W of A^n can be of the form A^n\f(A^n)? (Algebraic) Oka theory has provided a lot evidences towards the conjecture that indeed all subvarieties of codimension at least 2 will be of this form. This talk, joint work with Viktor Balch Barth, proves the following: for any W of codimension at least 2, there is an f such that A^n\f(A^n) is a closed algebraic subvariety of A^n which is birationally equivalent to W. 

March 21  13:00. 

Speaker: Thang Nguyen

Venue (Same preocedure)

Tile: TBA

Abstract: TBA

Published Feb. 16, 2024 12:50 PM - Last modified Feb. 16, 2024 12:50 PM