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In this article, we functorially associate definable sets to $k$-analytic curves, and definable maps to analytic morphisms between them, for a large class of $k$-analytic curves. Given a $k$-analytic curve $X$, our association allows us to…

Algebraic Geometry · Mathematics 2023-06-22 Pablo Cubides Kovacsics , Jérôme Poineau

Given a purely contractive matrix-valued analytic function $\Theta$ on the unit disc $\bm{D}$, we study the $\mc{U} (n)$-parameter family of unitary perturbations of the operator $Z_\Theta$ of multiplication by $z$ in the Hilbert space…

Functional Analysis · Mathematics 2011-07-19 R. T. W. Martin

Contraction of an edge merges its end points into a new vertex which is adjacent to each neighbor of the end points of the edge. An edge in a $k$-connected graph is {\em contractible} if its contraction does not result in a graph of lower…

Discrete Mathematics · Computer Science 2009-02-10 N. S. Narayanaswamy , N. Sadagopan , Apoorve Dubey

We show that there exist non-compact composition operators in the connected component of the compact ones on the classical Hardy space $H^2$ on the unit disc. This answers a question posed by Shapiro and Sundberg in 1990. We also establish…

Functional Analysis · Mathematics 2007-06-20 Eva A. Gallardo-Gutiérrez , Maria J. González , Pekka Nieminen , Eero Saksman

It is proved an inequality - integrated analogue of the Hardy inequality and as application simplified proof of the theorem of S. A. Vinogradov for the bounded Toeplitz operators on the space of functions analytic and bounded in the unit…

Complex Variables · Mathematics 2008-08-20 Peyo Stoilov

We study Clark measures on the unit polydisc, giving an overview of recent research and investigating the Clark measures of some new examples of multivariate inner functions. In particular, we study the relationship between Clark measures…

Complex Variables · Mathematics 2023-09-15 Nell Jacobsson

Given a bounded symmetric domain $D$ in $\mathbb C^n$, we consider the Clark measures $\mu_\alpha$, $\alpha\in \mathbb T$, associated with a rational inner function $\varphi$ from $D$ into the unit disc in $\mathbb C$. We show that…

Complex Variables · Mathematics 2025-05-05 Mattia Calzi

We show that the unit ball of a Hilbert space in its weak topology is a continuous image of the countable power of the Alexandroff compactification of a discrete set, and we deduce some combinatorial properties of its lattice of open sets…

General Topology · Mathematics 2009-03-03 Antonio Avilés

We study the interplay between the backward dynamics of a non-expanding self-map $f$ of a proper geodesic Gromov hyperbolic metric space $X$ and the boundary regular fixed points of $f$ in the Gromov boundary. To do so, we introduce the…

Complex Variables · Mathematics 2024-02-08 Leandro Arosio , Matteo Fiacchi , Lorenzo Guerini , Anders Karlsson

An oriented compact closed manifold is called inflexible if the set of mapping degrees ranging over all continuous self-maps is finite. Inflexible manifolds have become of importance in the theory of functorial semi-norms on homology.…

Algebraic Topology · Mathematics 2011-09-06 Manuel Amann

We establish some estimates of the the angular derivatives from below for holomorphic self-maps of the unit disk at one and two fixed points of the unit circle provided there is no fixed point inside the unit disk. The results complement…

Complex Variables · Mathematics 2013-09-13 A. Frolova , M. Levenshtein , D. Shoikhet , A. Vasil'ev

We consider infinite graphs and the associated energy forms. We show that a graph is canonically compactifiable (i.e. all functions of finite energy are bounded) if and only if the underlying set is totally bounded with respect to any…

Metric Geometry · Mathematics 2020-09-28 Simon Puchert

For $1/2<p<1$, a description of inner functions whose derivative is in the Hardy space $H^p$ is given in terms of either their mapping properties or the geometric distribution of their zeros.

Complex Variables · Mathematics 2018-10-01 Janne Gröhn , Artur Nicolau

In this article, we study mappings acting between domains of two factor spaces by certain groups of M\"{o}bius automorphisms of the unit ball that act discontinuously and do not have fixed points. For such mappings, we have established…

Complex Variables · Mathematics 2019-06-06 Evgeny Sevost'yanov

The classical Gauss--Lucas theorem describes the location of the critical points of a polynomial. There is also a hyperbolic version, due to Walsh, in which the role of polynomials is played by finite Blaschke products on the unit disk. We…

Complex Variables · Mathematics 2019-09-04 Konstantin M. Dyakonov

For a large class of unitarily invariant reproducing kernel functions $K$ on the unit ball $\mathbb B_d$ in $\mathbb C^d$, we characterize the $K$-inner functions on $\mathbb B_d$ as functions admitting a suitable transfer function…

Functional Analysis · Mathematics 2019-12-20 Jörg Eschmeier , Sebastian Toth

It is known that the hyperbolic plane admits a countable infinity of compactifications into a closed disk such that the isometric action of SL(2;R) acts analytically on the compactified space. We prove that among those compactifications,…

Metric Geometry · Mathematics 2009-01-05 Benoit Kloeckner

Let $f$ be a function that is analytic in the unit disc. We give new estimates, and new proofs of existing estimates, of the Euclidean length of the image under $f$ of a radial segment in the unit disc. Our methods are based on the…

Complex Variables · Mathematics 2014-02-26 A. F. Beardon , T. K. Carne

Let u be a subharmonic function in D={|z|<1}. There exist an absolute constant C and an analytic function f in D such that \int_D |u(z)-log|f(z)|| dm(z)<C where m denotes the plane Lebesgue measure. We also consider uniform approximation.

Complex Variables · Mathematics 2008-07-08 Igor Chyzhykov

Radius constants for several classes of analytic functions on the unit disk are obtained. These include the radius of starlikeness of a positive order, radius of parabolic starlikeness, radius of Bernoulli lemniscate starlikeness, and…

Complex Variables · Mathematics 2012-10-18 Rosihan M. Ali , Naveen Jain , V. Ravichandran