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The article is devoted to investigation of classes of functions monotone as functions on general $C^*$-algebras that are not necessarily the $C^*$-algebras of all bounded linear operators on a Hilbert space as it is in classical case of…

Operator Algebras · Mathematics 2007-05-23 Hiroyuki Osaka , Sergei D. Silvestrov , Jun Tomiyama

We prove the Hardy-Littlewood theorem in two dimensions for functions whose Fourier coefficients obey general monotonicity conditions and, importantly, are not necessarily positive. The sharpness of the result is given by a counterexample,…

Classical Analysis and ODEs · Mathematics 2023-10-06 Kristina Oganesyan

We prove a fixed-point theorem that generalises and simplifies a number of results in the theory of $F$-contractions. We show that all of the previously imposed conditions on the operator can be either omitted or relaxed. Furthermore, our…

Classical Analysis and ODEs · Mathematics 2019-03-22 Sándor Kajántó , Andor Lukács

Let $f \geq 0$ be operator monotone on $[0, \infty)$. In this paper we prove that for any unitarily-invariant norm $|||-|||$ on $M_n(\mathbb{C})$ and matrices $A, B, X \in M_n(\mathbb{C})$ with $A, B \geq 0$ and $|||X||| \leq 1$,…

Functional Analysis · Mathematics 2023-11-30 David Herrera

In this paper, we shall consider the notion of bicomplex inner product and define bicomplex Hilbert space. We shall define $L^{2}[a,b]$ where the functions take bicomplex values. We shall prove the Theorem for a bounded self adjoint…

Functional Analysis · Mathematics 2024-02-27 Akshay Sakharam Rane

In this paper, we obtain the subadditivity inequality of strongly operator convex functions on $(0, \infty)$ and $(-\infty,0)$. Applying the properties of operator convex functions, we deduce the subadditivity property of operator monotone…

Functional Analysis · Mathematics 2024-05-10 Nahid Gharakhanlu , Mohammad Sal Moslehian

By solving a free analog of the Monge-Amp\`ere equation, we prove a non-commutative analog of Brenier's monotone transport theorem: if an $n$-tuple of self-adjoint non-commutative random variables $Z_{1},...,Z_{n}$ satisfies a regularity…

Operator Algebras · Mathematics 2013-10-09 A. Guionnet , D. Shlyakhtenko

We generalize the Omori-Yau almost maximum principle of the Laplace-Beltrami operator on a complete Riemannian manifold $M$ to a second-order linear semi-elliptic operator $L$ with bounded coefficients and no zeroth order term. Using this…

Differential Geometry · Mathematics 2013-06-19 Kyusik Hong , Chanyoung Sung

The object of this paper is to prove a version of the Beurling-Helson-Lowdenslager invariant subspace theorem for operators on certain Banach spaces of functions on a multiply connected domain in the complex plane. The norms for these…

Functional Analysis · Mathematics 2016-07-06 Yanni Chen , Don Hadwin , Zhe Liu , Eric Nordgren

The main result of this paper is the extension of the Schur-Horn Theorem to infinite sequences: For two nonincreasing nonsummable sequences x and y that converge to 0, there exists a compact operator A with eigenvalue list y and diagonal…

Operator Algebras · Mathematics 2009-05-22 Victor Kaftal , Gary Weiss

Our main result is a theorem saying that a bounded operator $A$ on a Hilbert space belongs to a certain set associated with its self-commutator $[A^*,A]$, provided that $A-zI$ can be approximated by invertible operators for all complex…

Operator Algebras · Mathematics 2009-10-25 N. Filonov , Y. Safarov

We define Letac-Wesolowski-Matsumoto-Yor (LWMY) functions as decreasing functions from $(0,\infty)$ onto $(0,\infty)$ with the following property: there exist independent, positive random variables $X$ and $Y$ such that the variables…

Statistics Theory · Mathematics 2012-03-05 A. E. Koudou , P. Vallois

We show that Lieb's concavity theorem holds more generally for any unitary invariant matrix function $\phi:\mathbf{H}_+^n\rightarrow \mathbb{R}_+^n$ that is concave and satisfies H\"older's inequality. Concretely, we prove the joint…

Functional Analysis · Mathematics 2019-05-08 De Huang

Let $X$, $Y$ be Banach spaces and let $\mathcal{L}(X,Y)$ be the space of bounded linear operators from $X$ to $Y$. We develop the theory of double operator integrals on $\mathcal{L}(X,Y)$ and apply this theory to obtain commutator estimates…

Functional Analysis · Mathematics 2016-04-22 Jan Rozendaal , Fedor Sukochev , Anna Tomskova

Given a linear semi-bounded symmetric operator $S\ge -\omega$, we explicitly define, and provide their nonlinear resolvents, nonlinear maximal monotone operators $A_\Theta$ of type $\lambda>\omega$ (i.e. generators of one-parameter…

Functional Analysis · Mathematics 2015-04-20 Andrea Posilicano

Some differential implications of classical Marx-Strohh\"acker theorem are extended for multivalent functions. These results are also generalized for functions with fixed second coefficient by using the theory of first order differential…

Complex Variables · Mathematics 2021-03-23 Prachi Gupta , Sumit Nagpal , V. Ravichandran

We consider a matrix semigroup $T: [0,\infty) \to \mathbb{R}^{d \times d}$ without assuming any measurability properties and show that, if $T$ is bounded close to $0$ and $T(t) \ge 0$ entrywise for all $t$, then $T$ is continuous. This…

Functional Analysis · Mathematics 2025-02-20 Jochen Glück

We introduce an generalized action functional describing the equations of motion and the variational equations for any Lagrangian system. Using this novel scheme we are able to generalize Noether's theorem in such a way that to any…

Mathematical Physics · Physics 2016-09-07 C. M. Arizmendi , J. Delgado , H. N. Núñez-Yépez , A. L. Salas-Brito

This article is centered around generalizing a previous implicit function theorem of the author to be applicable for maps f:E sqcap F to F which can be lifted to Keller C^k_pi maps f_i:E sqcap F_i to F_i with F_i Banach and F=projlim F_i .…

Functional Analysis · Mathematics 2007-05-23 Seppo I Hiltunen

Noncommutative functions are graded functions between sets of square matrices of all sizes over two vector spaces that respect direct sums and similarities. They possess very strong regularity properties (reminiscent of the regularity…

Functional Analysis · Mathematics 2020-05-20 Dmitry Kaliuzhnyi-Verbovetskyi , Leonard Stevenson , Victor Vinnikov