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M. D. Acosta

Publications and source records attributed to M. D. Acosta.

7 recordsLinked to original sources
arXiv2021

Bishop-Phelps-Bollobás property for positive functionals

We introduce the so-called Bishop-Phelps-Bollobás property for positive functionals, a particular case of the Bishop-Phelps-Bollobás property for positive operators. First we show a version of the Bishop-Phelps-Bollobás theorem for positive elements and positive functionals in the dual of any Banach lattice. We also characterize the strong Bishop-Phelps-Bollobás property for positive functionals in a Banach lattice. We prove that any finite-dimensional Banach lattice has the the Bishop-Phelps-Bollobás property for positive functionals. A sufficient and a necessary condition to have the Bishop-Phelps-Bollobás property for positive functionals are also provided. As a consequence of this result, we obtain that the spaces $L_p(μ)$ ($1\le p < \infty$), for any positive measure $μ,$ $C(K)$ and $\mathcal{M} (K)$, for any compact and Hausdorff topological space $K,$ satisfy the Bishop-Phelps-Bollobás property for positive functionals. We also provide some more clarifying examples.

math.FA↗
arXiv2019

Bishop-Phelps-Bollobás property for positive operators when the domain is $L_\infty $

We prove that the class of positive operators from $L_\infty (μ)$ to $Y$ has the Bishop-Phelps-Bollobás property for any positive measure $μ$, whenever $Y$ is a uniformly monotone Banach lattice with a weak unit. The same result also holds for the pair $(c_0, Y)$ for any uniformly monotone Banach lattice $Y.$ Further we show that these results are optimal in case that $Y$ is strictly monotone.

math.FA↗
arXiv2018

A basis of $\R ^n$ with good isometric properties and some applications to denseness of norm attaining operators

We characterize real Banach spaces $Y$ such that the pair $(\ell_\infty ^n, Y)$ has the Bishop-Phelps-Bollobás property for operators. To this purpose it is essential the use of an appropriate basis of the domain space $\R^n$. As a consequence of the mentioned characterization, we provide examples of spaces $Y$ satisfying such property. For instance, finite-dimensional spaces, uniformly convex spaces, uniform algebras and $L_1(μ)$ ($μ$ a positive measure) satisfy the previous property.

math.FA↗
arXiv2018

On the continuity of the composition operation on spaces of holomorphic mappings

We discuss the continuity of the composition on several spaces of holomorphic mappings on open subsets of a complex Banach space. On the Fréchet space of the entire mappings that are bounded on bounded sets the composition turns to be even holomorphic. In such space we consider linear subspaces closed under left and right composition. We discuss the relationship of such subspaces with ideals of operators and give several examples of them. We also provide natural examples of spaces of holomorphic mappings where the composition is not continuous.

math.FA↗
arXiv2017

The Bishop-Phelps-Bollobás and approximate hyperplane series properties

We study the Bishop-Phelps-Bollobás property for operators between Banach spaces. Sufficient conditions are given for generalized direct sums of Banach spaces with respect to a~uniformly monotone Banach sequence lattice to have the approximate hyperplane series property. This result implies that Bishop-Phelps-Bollobás theorem holds for operators from $\ell_1$ into such direct sums of Banach spaces. We also show that the direct sum of two spaces with the approximate hyperplane series property has such property whenever the norm of the direct sum is absolute.

math.FA↗
arXiv2017

The Bishop-Phelps-Bollob{á}s property for numerical radius of operators on $L_1 (μ)$

In this paper, we introduce the notion of the Bishop-Phelps-Bollobás property for numerical radius (BPBp-$ν$) for a subclass of the space of bounded linear operators. Then, we show that certain subspaces of $\mathcal{L}(L_1(μ))$ have the BPBp-$ν$ for every finite measure $μ$. As a consequence we deduce that the subspaces of finite-rank operators, compact operators and weakly compact operators on $L_1(μ)$ have the BPBp-$ν$.

math.FA↗