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We construct continuous (and even invertible) linear operators acting on Banach (even Hilbert) spaces whose restrictions to their respective closed linear subspaces of chain recurrent vectors are not chain recurrent operators. This…

Functional Analysis · Mathematics 2025-04-03 Antoni López-Martínez , Dimitris Papathanasiou

A tuple $(T_1,\dots,T_n)$ of continuous linear operators on a topological vector space $X$ is called hypercyclic if there is $x\in X$ such that the the orbit of $x$ under the action of the semigroup generated by $T_1,\dots,T_n$ is dense in…

Dynamical Systems · Mathematics 2010-08-23 Stanislav Shkarin

Let $V$ be a strongly regular vertex operator algebra. For a state $h \in V_1$ satisfying appropriate integrality conditions, we prove that the space spanned by the trace functions Tr$_Mq^{L(0)-c/24}\zeta^{h(0)} ($M$ a $V$-module) is a…

Quantum Algebra · Mathematics 2015-08-27 Matthew Krauel , Geoffrey Mason

Let $B$, $I$ be the unweighted backward shift and the identity operator respectively on $l^{\infty}(\mathbb{N})$, the space of bounded sequences over the complex numbers endowed with the supremum norm. We prove that $I+\lambda B$ is locally…

Functional Analysis · Mathematics 2013-02-08 George Costakis , Antonios Manoussos , Amir Bahman Nasseri

Let $B$ be an unilateral weighted backward shift on $\ell_p$, $1 \leq p < \infty$, that admits a $\mathscr{U}$-frequently hypercyclic subspace. We prove that $B$ admits such a subspace free of frequently hypercyclic vectors. The proof…

Functional Analysis · Mathematics 2026-05-11 Nacib G. Albuquerque , Thiago R. Alves , Geraldo Botelho , Vinícius V. Fávaro

The operators on $\ell_{\infty}$ which are commutators are those not of the form $\lambda I + S$ with $\lambda\neq 0$ and $S$ strictly singular.

Functional Analysis · Mathematics 2009-07-27 Detelin Dosev , William B. Johnson

Operators such as Carleson operator are known to be bounded on $L^p$ for all $1<p<\infty$, but not from $L^1$ to weak-$L^1$ and from $H^p$ to $L^p$ for each $0<p\leq 1$, the object of this article is to give a estimate for all $0<p<\infty$.…

Classical Analysis and ODEs · Mathematics 2021-08-16 Shunchao Long

The question if polynomially bounded operator is similar to a contraction was posed by Halmos and was answered in the negative by Pisier. His counterexample is an operator of infinite multiplicity, while all its restrictions on invariant…

Functional Analysis · Mathematics 2019-06-03 Maria Gamal'

In this note, we define a bounded variant on the Hilbert projective metric on an infinite dimensional space $E$ and study the contraction properties of the projective maps associated with positive linear operators on $E$. More precisely, we…

Functional Analysis · Mathematics 2025-02-07 Maxime Ligonnière

We show that several convolution operators on the space of entire functions, such as the MacLane operator, support a dense hypercyclic algebra that is not finitely generated. Birkhoff's operator also has this property on the space of…

Functional Analysis · Mathematics 2019-03-26 Juan Bès , Dimitris Papathanasiou

The notion of a Levi operator is an operator abstraction of the Levy property of a norm or, more generally of the Levi topology on a locally solid vector lattice. Various aspects of Levi operators have been studied recently by several…

Functional Analysis · Mathematics 2025-06-24 Eduard Emelyanov

We provide an alternative proof to those by Shkarin and by Bayart and Matheron that the operator $D$ of complex differentiation supports a hypercyclic algebra on the space of entire functions. In particular we obtain hypercyclic algebras…

Functional Analysis · Mathematics 2019-03-26 Juan Bès , José Alberto Conejero , Dimitrios Papathanasiou

We study operator log-convex functions on $(0,\infty)$, and prove that a continuous nonnegative function on $(0,\infty)$ is operator log-convex if and only if it is operator monotone decreasing. Several equivalent conditions related to…

Functional Analysis · Mathematics 2014-12-23 Tsuyoshi Ando , Fumio Hiai

We study the representation of non-weakly compact operators between $AL$-spaces. In this setting, we show that every operator admits a best approximant in the ideal of weakly compact operators. Using duality arguments, we extend this result…

Functional Analysis · Mathematics 2026-03-30 Antonio Acuaviva , Amir Bahman Nasseri

We provide with criteria for a family of sequences of operators to share a frequently universal vector. These criteria are variants of the classical Frequent Hypercyclicity Criterion and of a recent criterion due to Grivaux, Matheron and…

Functional Analysis · Mathematics 2021-02-05 Stéphane Charpentier , Romuald Ernst , Monia Mestiri , Augustin Mouze

We prove that for operators satistying weighted inequalities with $A_p$ weights the boundedness on a certain class of Morrey spaces holds with weights of the form $|x|^\alpha w(x)$ for $w\in A_p$. In the case of power weights the shift with…

Functional Analysis · Mathematics 2019-10-30 Javier Duoandikoetxea , Marcel Rosenthal

In this paper, we study the boundedness theory for maximal Calder\'on-Zygmund operators acting on noncommutative $L_p$-spaces. Our first result is a criterion for the weak type $(1,1)$ estimate of noncommutative maximal Calder\'on-Zygmund…

Classical Analysis and ODEs · Mathematics 2020-10-21 Guixiang Hong , Xudong Lai , Bang Xu

In this paper, we are interested in the properties of a new class of operators, recently introduced by Shkarin, called strongly $n$-supercyclic operators. This notion is stronger than $n$-supercyclicity. We prove that such operators have…

Functional Analysis · Mathematics 2014-01-07 Romuald Ernst

This work studies operators mapping vector and scalar fields defined over a manifold $\mathcal{M}$, and which commute with its group of diffeomorphisms $\text{Diff}(\mathcal{M})$. We prove that in the case of scalar fields…

Machine Learning · Computer Science 2025-12-17 Grégoire Sergeant-Perthuis , Jakob Maier , Joan Bruna , Edouard Oyallon

We develop a unified framework for constructing matrix approximations to the convolution operator of Volterra type defined by functions that are approximated using classical orthogonal polynomials on $[-1, 1]$. The numerically stable…

Numerical Analysis · Mathematics 2018-08-17 Kuan Xu , Ana Loureiro