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We consider an extremal problem for polynomials, which is dual to the well-known Smale mean value problem. We give a rough estimate depending only on the degree.

Complex Variables · Mathematics 2009-06-26 Vladimir Dubinin , Toshiyuki Sugawa

In this paper, we improve the lower estimate of multidimensional Bohr radius for unit ball of $\ell^n_q$-spaces ($1\leq q\leq \infty$) for bounded holomorphic functions with values in finite dimensional complex Banach spaces. The new…

Complex Variables · Mathematics 2025-07-01 Vasudevarao Allu , Subhadip Pal

In this paper, we study the Bohr inequality with lacunary series to the single valued (resp. vector-valued) holomorphic function defined in unit ball of finite dimensional Banach sequence space. Also, we extend the Bohr inequality with an…

Complex Variables · Mathematics 2024-04-30 Shankey Kumar , Saminathan Ponnusamy , G. Brock Williams

We study the numerical index of absolute sums of Banach spaces, giving general conditions which imply that the numerical index of the sum is less or equal than the infimum of the numerical indices of the summands and we provide some…

Functional Analysis · Mathematics 2010-03-18 Miguel Martín , Javier Merí , Mikhail Popov , Beata Randrianantoanina

We display methods that allow for computations of spectra, pseudospectra and resolvents of linear operators on Hilbert spaces and also elements in unital Banach algebras. The paper considers two different approaches, namely, pseudospectral…

Numerical Analysis · Mathematics 2016-10-25 Anders C. Hansen , Olavi Nevanlinna

In this paper, we study a more general version of multidimensional Bohr radii for the holomorphic functions defined on unit ball of $\ell^n_q\,\,(1\leq q\leq \infty)$ spaces with values in arbitrary complex Banach spaces. More precisely, we…

Functional Analysis · Mathematics 2026-04-14 Vasudevarao Allu , Subhadip Pal

It is a longstanding problem whether every contractible Banach algebra is necessarily finite-dimensional. In this note, we confirm this for Banach algebras acting on Banach spaces with the uniform approximation property. This generalizes a…

Functional Analysis · Mathematics 2011-10-31 Narutaka Ozawa

We introduce the operators "modified limit" and "accumulation" on a Banach space, and we use this to define what we mean by being internally computable over the space. We prove that any externally computable function from a computable…

Logic · Mathematics 2015-07-01 Dag Normann

We study the spectrum $M_b(U)$ of the algebra of bounded type holomorphic functions on a complete Reinhardt domain in a symmetrically regular Banach space $E$ as an analytic manifold over the bidual of the space. In the case that $U$ is the…

Functional Analysis · Mathematics 2018-11-13 Daniel Carando , Daniela M. Vieira , Santiago Muro

We lift upper and lower estimates from linear functionals to $n$-homogeneous polynomials and using this result show that $l_\infty$ is finitely represented in the space of $n$-homogeneous polynomials, $n\ge2$, for any infinite dimensional…

Functional Analysis · Mathematics 2009-09-25 Sean Dineen

We survey large value problems, including the large value problem for Dirichlet polynomials, the restriction problem, and problems from computer science. We describe known techniques and open problems, drawing on perspectives from all three…

Number Theory · Mathematics 2025-03-11 Larry Guth

In this article, we study the multi-dimensional Bohr radii of holomorphic functions defined on the Banach sequence spaces with values in the Banach spaces. For the case of finite dimensional Banach spaces, we exhibit the exact asymptotic…

Functional Analysis · Mathematics 2023-03-31 Shankey Kumar , Ramesh Manna

Let $R$ be a commutative complex unital semisimple Banach algebra with the involution $\cdot ^\star$. Sufficient conditions are given for the existence of a stabilizing solution to the $H^\infty$ Riccati equation when the matricial data has…

Optimization and Control · Mathematics 2011-07-28 Amol Sasane

Under certain hypotheses on the Banach space $X$, we prove that the set of analytic functions in $\mathcal{A}_u(X)$ (the algebra of all holomorphic and uniformly continuous functions in the ball of $X$) whose Aron-Berner extensions attain…

Functional Analysis · Mathematics 2015-04-07 Daniel Carando , Martin Mazzitelli

We develop a theory of Valuation Hilbert Modules and prove a version of Beurling's theorem for these. Then we apply our version of Beurling's theorem to obtain complete descriptions of the closed invariant subspaces of a number of Hilbert…

Complex Variables · Mathematics 2023-06-23 Charles W. Neville

We study multiplier algebras for a large class of Banach algebras which contains the group algebra $L_1(G)$, the Beurling algebras $L_1(G, \omega)$, and the Fourier algebra $A(G)$ of a locally compact group $G$. This study yields numerous…

Functional Analysis · Mathematics 2014-02-26 Zhiguo Hu , Matthias Neufang , Zhong-Jin Ruan

This is an attempt to build Banach space valued theory for certain singular integrals on Hamming cube. Of course all estimates below are dimension independent, and we tried to find ultimate sharp assumptions on the Banach space for a…

Functional Analysis · Mathematics 2022-04-27 Paata Ivanisvili , Alexander Volberg

In this paper, we study the Bohr inequality with lacunary series for vector-valued holomorphic functions defined in unit ball of finite dimensional Banach sequence space. Also, we study the Bohr-Rogosinski inequality for same class of…

Complex Variables · Mathematics 2025-09-05 Sabir Ahammed , Molla Basir Ahamed , Rajesh Hossain

This paper deals with a general form of variational problems in Banach spaces which encompasses variational inequalities as well as minimization problems. We prove a characterization of local error bounds for the distance to the…

Optimization and Control · Mathematics 2018-07-12 Christian Kanzow , Daniel Steck

This paper systematically studies Hilbert boundary value problems for hyper monogenic functions on the hyperplane for the solutions being of any integer orders at the infinity, where the negative order cases are new even when restricted to…

Complex Variables · Mathematics 2022-03-01 Pei Dang , Jinyuan Du , Tao Qian