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Let $h$ be a harmonic function defined on a spherical disk. It is shown that $\Delta^k |h|^2$ is nonnegative for all $k\in \mathbb{N}$ where $\Delta$ is the Laplace-Beltrami operator. This fact is generalized to harmonic functions defined…

Spectral Theory · Mathematics 2023-12-05 Gabor Lippner , Dan Mangoubi , Zachary McGuirk , Rachel Yovel

We study the closure in the Hardy space or the disk algebra of algebras generated by two bounded functions, of which one is a finite Blaschke product. We give necessary and sufficient conditions for density or finite codimension of such…

Complex Variables · Mathematics 2007-05-23 Michael I. Stessin , Pascal J. Thomas

We consider the space of real-valued continuously differentiable functions on a compact subset of a euclidean space. We characterize the completeness of this space and prove that the space of restrictions of continuously differentiable…

Classical Analysis and ODEs · Mathematics 2020-06-18 Leonhard Frerick , Laurent Loosveldt , Jochen Wengenroth

We establish the $L^2$ theory for the Cauchy-Riemann equations on product domains provided that the Cauchy-Riemann operator has closed range on each factor. We deduce regularity of the canonical solution on $(p,1)$-forms in special Sobolev…

Complex Variables · Mathematics 2010-05-11 Debraj Chakrabarti , Mei-Chi Shaw

We introduce $p$-adic Kummer spaces of continuous functions on $\mathbb{Z}_p$ that satisfy certain Kummer type congruences. We will classify these spaces and show their properties, for instance, ring properties and certain decompositions.…

Number Theory · Mathematics 2009-10-07 Bernd C. Kellner

We study a two-dimensional conformal field theory coupled to quantum gravity on a disk. Using the continuum Liouville field approach, we compute three-point correlation functions of boundary operators. The structure of momentum…

High Energy Physics - Theory · Physics 2009-10-22 Yoshiaki Tanii , Shun-ichi Yamaguchi

We study surfaces in Euclidean space constructed by the sum of two curves or that are graphs of the product of two functions. We consider the problem to determine all these surfaces with constant Gauss curvature. We extend the results to…

Differential Geometry · Mathematics 2014-10-10 Rafael López , Marilena Moruz

A d.c. (delta-convex) function on a normed linear space is a function representable as a difference of two continuous convex functions. We show that an infinite dimensional analogue of Hartman's theorem on stability of d.c. functions under…

Functional Analysis · Mathematics 2007-06-06 L. Vesely , L. Zajicek

In this paper we study the notion of Gerghaty type contractive mapping via simulation function along with $\mathcal{C}$-class functions and prove the existence of several fixed point results in ordinary and partially ordered metric spaces.…

Functional Analysis · Mathematics 2018-10-26 Azhar Hussain , Muhammad Ishfaq , Tanzeela Kanwal , Stojan Radenović

Let X be a complex manifold of dimension at least 2 which has an exhaustion function whose Levi form has at each point at least 2 positive eigenvalues. We prove that there are proper holomorphic discs in X through any given point

Complex Variables · Mathematics 2007-05-23 Barbara Drinovec Drnovsek

We show that any semi-calibration of degree 2 is locally induced by a smooth almost complex structure. We provide some applications of this result in the regularity theory for semi-calibrated 2-currents

Analysis of PDEs · Mathematics 2015-07-24 Costante Bellettini

By considering a fixed point in unit disk $\Delta$, a new class of univalent convex functions is defined. Coefficient inequalities, integral operator and extreme points of this class are obtained.

Complex Variables · Mathematics 2009-04-23 Sh. Najafzadeh , M. Eshaghi Gordji , A. Ebadian

A natural connection between rational functions of several real or complex variables, and subspace collections is explored. A new class of function, superfunctions, are introduced which are the counterpart to functions at the level of…

Algebraic Geometry · Mathematics 2016-02-23 Graeme W. Milton

This paper introduces a novel class of topological spaces, termed SC*-regular spaces, which are defined using SC*-open sets. We explore their fundamental properties and examine their connections with existing regularity concepts, such as…

General Topology · Mathematics 2025-05-16 Neeraj Kumar Tomar , Amit Ujlayan , M. C. Sharma

Let $D$ be the open unit disc in the complex plane. We denote by $\mathbb{C}$ the set of complex numbers and consider any compact set $K$ which is disjoint from $D$ and which also has connected complement. Let $A(K)$ denote all the…

Complex Variables · Mathematics 2015-06-05 Nikos Tsirivas

We generalize some classical results about quasicontinuous and separately continuous functions with values in metrizable spaces to functions with values in certain generalized metric spaces, called Maslyuchenko spaces. We establish…

General Topology · Mathematics 2021-11-01 Taras Banakh

We consider a semi-algebraic function defined on a closed semi-algebraic set X. We give formulas relating the topology of X to the indices of the critical points of the function and to the topological behavior of the function at infinity.…

Algebraic Geometry · Mathematics 2010-12-10 Nicolas Dutertre

We discuss the problem of when a continuous map between topological spaces induces a continuous function between their respective hyperspaces. We characterize the continuity of the induced function in the case of the Fell and Attouch-Wets…

General Topology · Mathematics 2021-04-28 Victor Donjuán , Natalia Jonard-Pérez , Ananda López-Poo

We establish existence and regularity results for normal Coulomb frames in the normal bundle of two-dimensional surfaces of disc-type embedded in Euclidean spaces of higher dimensions.

Differential Geometry · Mathematics 2009-10-13 Steffen Froehlich

In this paper, a study of topological and algebraic properties of two families of functions from the unit interval $I$ into the plane $\mathbb{R}^2$ is performed. The first family is the collection of all Peano curves, that is, of those…

General Topology · Mathematics 2017-12-19 L. Bernal-González , M. C. Calderón-Moreno , J. A. Prado-Bassas