Banach space valued mean periodic functions

Banach Algebras of Vector-valued Functions

We introduce the concept of an $E$-valued function algebra, a type of Banach algebra that consist of continuous $E$-valued functions on some compact Hausdorff space, where $E$ is a Banach algebra. We present some basic results about such algebras, having to do with the Shilov boundary and the set of peak points of some commutative $E$-valued function algebras. We give some specific examples.

Relative reproducing kernels in vector-valued Hilbert and Banach spaces

This paper is devoted to the study of vector valued reproducing kernel Hilbert spaces. We focus on reproducing kernels in vector-valued reproducing kernel Hilbert spaces. In particular we extend reproducing kernels to relative reproducing kernels and prove some theorems in this subject.

$C^{\ast}-$algebra structure on vector valued-Banach algebras

Let $A$ be a commutative semisimple Banach algebra, $X$ be a locally compact Hausdorff topological space and $G$ be a locally compact topological group. In this paper, we investigate several properties of vector valued Banach algebras $C_0(X,A)$, $L^p(G,A)$, $l^p(X,A)$ and $l^{\infty}(X,A)$. We prove that these algebras are isomorphic with a $C^*-$algebra if and only if $A$ is so.

Modular convergence in $H$-Orlicz spaces of Banach valued functions

In this article we develop the theory of $H$-Orlicz space generated by generalised Young function. Modular convergence of $H$-Orlicz space for the case of vector-valued functions and norm convergence in $\mcH^θ(X, \barμ)$ where $X$ is any Banach space are discussed. Relationships of modular convergence and norm convergence of $H$-Orlicz spaces are discussed.

Kuelbs-Steadman spaces for Banach space-valued measures

We introduce Kuelbs-Steadman-type spaces for real-valued functions, with respect to countably additive measures, taking values in Banach spaces. We investigate their main properties and embeddings in $L^p$-type spaces, considering both the norm associated to norm convergence of the involved integrals and that related to weak convergence of the integrals.

$L_{1}$- Properties of vector-valued Banach algebras

Let $G$ be a locally compact group and $A$ be a commutative semisimple Banach algebra over the scalar field $\mathbb{C}$. The correlation between different types of $BSE$- Banach algebras $A$, and the Banach algebras $L^{1}(G, A)$ are assessed. It is found and approved that $M(G, A) = L^{1}(G, A)$ if and only if $G$ is discrete. Furthermore, some properties of vector-valued measure algebras on groups are given, so that $M(G, A)$ is a convolution measure algebra.

On the character space of Banach vector-valued function algebras

Given a compact space $X$ and a commutative Banach algebra $A$, the character spaces of $A$-valued function algebras on $X$ are investigated. The class of natural $A$-valued function algebras, those whose characters can be described by means of characters of $A$ and point evaluation homomorphisms, is introduced and studied. For an admissible Banach $A$-valued function algebra $\mathcal{A}$ on $X$, conditions under which the character space $M(\mathcal{A})$ is homeomorphic to $M(\mathfrak{A}) \times M(A)$ are presented, where $\mathfrak{A}=C(X) \cap \mathcal{A}$ is the subalgebra of $\mathcal{A…

Vector-valued Sobolev spaces based on Banach function spaces

It is known that for Banach valued functions there are several approaches to define a Sobolev class. We compare the usual definition via weak derivatives with the Reshetnyak-Sobolev space and with the Newtonian space; in particular, we provide sufficient conditions when all three agree. As well we revise the difference quotient criterion and the property of Lipschitz mapping to preserve Sobolev space when it acting as a superposition operator.

$C^{*}$- properties of vector-valued Banach algebras

Let $X$ be a locally compact Hausdorff space, and $A$ be a commutative semisimple Banach algebra over the scalar field $\mathbb{C}$. The correlation between different types of BSE- Banach algebras $A$, and the Banach algebra $C_{0}(X, A)$ are assessed. It is found and approved that $C_{0}(X, A)$ is a $C^{*}$- algebra if and only if $A$ is so. Furthermore, $C_{b}(X, A)= C_{0}(X, A)$ if and only if $X$ is compact.

对“关于定义在 Banach 空间闭子集上的向量值函数的光滑延拓” [Math. Ann. (2013) 355: 1201--1219] 的勘误

Corrigendum to "On Smooth extensions of vector-valued functions defined on closed subsets of Banach spaces" [Math. Ann. (2013) 355: 1201--1219]

本文是对2013年发表于Math. Ann.关于Banach空间闭子集上向量值函数光滑延拓论文的勘误说明。

球巴拿赫函数空间上的向量值哈代-利特尔伍德极大不等式

Vector-Valued Hardy--Littlewood Maximal Inequalities on Ball Banach Function Spaces

本文通过向量值极大不等式刻画非中心哈代-利特尔伍德极大算子在球巴拿赫函数空间及其Köthe伴随空间上的有界性，所得结果补充了Nieraeth的近期研究成果。

Isometries on Banach algebras of $C(Y)$-valued maps

We propose a unified approach to the study of isometries on algebras of vector-valued Lipschitz maps and those of continuously differentiable maps by means of the notion of natural $C(Y)$-valuezations that take values in unital commutative $C^*$-algebras. A precise proof of a theorem of Jarosz \cite{ja} is exhibited.

一般巴拿赫空间中集值度量投影的Mordukhovich导数与覆盖常数

Mordukhovich Derivatives and Covering Constant for Set-Valued Metric Projection in General Banach Spaces

本文得到l₁空间到其单位闭球的集值度量投影算子的显式表示，研究其Mordukhovich导数性质以计算覆盖常数，还针对二维巴拿赫空间得到该投影算子的显式解并详细计算其导数。

On Banach spaces of vector-valued random variables and their duals motivated by risk measures

We introduce Banach spaces of vector-valued random variables motivated from mathematical finance. So-called risk functionals are defined in a natural way on these Banach spaces and it is shown that these functionals are Lipschitz continuous. The risk functionals cannot be defined on strictly larger spaces of random variables which creates a particular interest for the spaces presented. We elaborate key properties of these Banach spaces and give representations of their dual spaces in terms of vector measures with values in the dual space of the state space.

On the lattice structure of the space of all Bochner integrable Banach lattice-valued functions

Suppose $(X,Σ,μ)$ is a finite measure space, $E$ is a Banach lattice, and $B(X,E,μ)$ is the space of all Bochner integrable $E$-valued functions. In this note, we show that $B(X,E,μ)$ is a $KB$-space or has the sequential Fatou property if and only if so is $E$. Among this, some results about Bochner integral convergence in $B(X,E,μ)$, using order structure of $E$, have been proved, as well.

一般 Banach 空间中集值度量投影算子的 Mordukhovich 导数

Mordukhovich derivatives of the set-valued metric projection operator in general Banach spaces

本文研究一般 Banach 空间中集值度量投影算子的 Mordukhovich 导数性质与精确解，并证明了 C[0, 1] 到多项式空间的投影为单值映射，进而探讨了其 Mordukhovich 导数与 Gateaux 方向导数。

Amenability properties of Banach algebra valued continuous functions

Let $X$ be a compact Hausdorff space and $A$ a Banach algebra. We investigate amenability properties of the algebra $C(X,A)$ of all $A$-valued continuous functions. We show that $C(X,A)$ has a bounded approximate diagonal if and only if $A$ has a bounded approximate diagonal; if $A$ has a compactly central approximate diagonal (unbounded) then $C(X,A)$ has a compactly approximate diagonal. Weak amenability of $C(X,A)$ for commutative $A$ is also considered.

Duality of certain Banach spaces of vector-valued holomorphic functions

In this work we study the vector-valued Hardy spaces H p (D; F) (1 \leq p \leq \infty) and their relationship with RNP, ARNP and the UMDP properties. By following the approach of Taylor in the scalar-valued case, we prove that, when F and F have the ARNP property, then H p (D; F) and H q (D; F) are canonically topologically isomorphic (for p, q \in (1, \infty) conjugate indices) if and only if F has the UMDP.

Heat equation for weighted Banach space valued function spaces

We study the homogeneous equation (*) $ u' = Δu$, $t > 0$, $u(0)=f\in wX$, where $wX$ is a weighted Banach space, $w(x)= (1+||x||)^k$, $x\in \r^n$ with $k\ge 0$, $ Δ$ is the Laplacian, $Y$ a complex Banach space and $X$ one of the spaces $ BUC (\r^n,Y)\} $, $ C_0 (\r^n,Y)$, $ L^p (\r^n,Y)$, $1 \le p < \infty$. It is shown that the mild solutions of (*) are still given by the classical Gauss-Poisson formula, a holomorphic $C_0$-semigroup.

Isometries on Banach algebras of vector-valued maps

We propose a unified approach to the study of isometries on algebras of vector-valued Lipschitz maps and those of continuously differentiable maps by means of the notion of admissible quadruples. We describe isometries on function spaces of some admissible quadruples that take values in unital commutative $C^*$-algebras. As a consequence we confirm the statement of \cite[Example 8]{jp} on Lipschitz algebras and show that isometries on such algebras indeed take the canonical form.

Vector-valued characters on Vector-valued Function Algebras

Let $A$ be a commutative Banach algebra and $X$ be a compact space. The class of Banach $A$-valued function algebras on $X$ consists of subalgebras of $C(X,A)$ with certain properties. We introduce the notion of $A$-characters on an $A$-valued function algebra $\A$ as homomorphisms from $\A$ into $A$ that basically have the same properties as the evaluation homomorphisms $\cE_x:f\mapsto f(x)$, with $x\in X$. For the so-called natural $A$-valued function algebras, such as $C(X,A)$ and $\Lip(X,A)$, we show that $\cE_x$ ($x\in X$) are the only $A$-characters. Vector-valued characters are utilized…

Banach空间中的微分与有序优化

Differentiation and Ordered Optimization in Banach Spaces

本文研究Banach空间中单值映射的广义临界点、有序极值及有序单调性，推导了lp空间和C[0,1]上多项式型和三角型算子的Gâteaux和Frechet导数公式，探讨了广义临界点与有序极值之间的联系，扩展了实值函数临界点与极值的关系。

Center of Banach algebra valued Beurling algebras

We prove that for a Banach algebra $A$ having a bounded $\mathcal{Z}(A)$-approximate identity and for every $\bf[IN]$ group $G$ with weight $w$ which is either constant on conjugacy classes or $w \geq 1$, $\mathcal{Z}\big(L^1_w(G) \otimes^γA\big) \cong \mathcal{Z}(L^1_w(G)) \otimes^γ\mathcal{Z}(A)$. As an application, we discuss the conditions under which $\mathcal{Z}\big(L^1_w(G,A)\big)$ enjoys certain Banach algebraic properties, for example, weak amenability, semisimplicity etc.

Toward an optimal theory of integration for quasi-Banach-space-valued functions

We present a new approach to define a suitable integral for functions with values in quasi-Banach spaces. The integrals of Bochner and Riemann have deficiencies in the non-locally convex setting. The study of an integral for $p$-Banach spaces initiated by Vogt is neither totally satisfactory, since there are quasi-Banach spaces which are $p$-convex for all $0<p<1$, so it is not always possible to choose an optimal $p$ to develop the integration. Our method puts the emphasis on the galb of the space, which permits a precise definition of its convexity. The integration works for all spaces of ga…

广义Banach空间中具有闭图的多值映射的不动点结果

Fixed point results for multivalued mapping with closed graphs in generalized Banach spaces

本文在广义Banach空间中建立多值映射上半连续性的新刻画，证明Perov型与Krasnoselskii型不动点定理，并应用于非线性包含系统。

On smooth extensions of vector-valued functions defined on closed subsets of Banach spaces

Let $X$ and $Z$ be Banach spaces, $A$ a closed subset of $X$ and a mapping $f:A \to Z$. We give necessary and sufficient conditions to obtain a $C^1$ smooth mapping $F:X \to Z$ such that $F_{\mid_A}=f$, when either (i) $X$ and $Z$ are Hilbert spaces and $X$ is separable, or (ii) $X^*$ is separable and $Z$ is an absolute Lipschitz retract, or (iii) $X=L_2$ and $Z=L_p$ with $1<p<2$, or (iv) $X=L_p$ and $Z=L_2$ with $2<p<\infty$.

Kluvánek-Lewis-Henstock integral in a Banach space

We investigate some properties and convergence theorem of Kluvánek-Lewis-Henstock $\m-$integrability for $\m-$measurable functions that we introduced in \cite{ABH}. We give a $\m-$a.e. convergence version of Dominated (resp. Bounded) Convergence Theorem for $\m.$ We introduce Kluvánek-Lewis-Henstock integrable of scalar-valued functions with respect to a set valued measure in a Banach space. Finally we introduce $(KL)-$type Dominated Convergence Theorem for the set-valued Kluvánek-Lewis-Henstock integral.

On the vector-valued Littlewood-Paley-Rubio de Francia inequality

The paper studies Banach spaces satisfying the Littlewood-Paley-Rubio de Francia property LPR_p, 2 \leq p < \infty. The paper shows that every Banach lattice whose 2-concavification is a UMD Banach lattice has this property. The paper also shows that every space having LPR_q also has LPR_p with q \leq p < \infty.

Banach Spaces with respect to Operator-Valued Norms

We introduce the notions of L(H)-valued norms and Banach spaces with respect to L(H)-valued norms. In particular, we introduce Hilbert spaces with respect to L(H)-valued inner products. In addition, we provide several fundamental examples of Hilbert spaces with respect to L(H)-valued inner products.

Vector-valued Walsh-Paley martingales and geometry of Banach spaces

The concept of Rademacher type $p$ ($1\leq p\leq2$) plays an important role in the local theory of Banach spaces. In \cite{mas88} Mascioni considers a weakening of this concept and shows that for a Banach space $X$ weak Rademacher type $p$ implies Rademacher type $r$ for all $r<p$. As with Rademacher type $p$ and weak Rademacher type $p$, we introduce the concept of Haar type $p$ and weak Haar type $p$ by replacing the Rademacher functions by the Haar functions in the respective definitions. We show that weak Haar type $p$ implies Haar type $r$ for all $r<p$. This solves a problem left open by…

Multi-task Learning in Vector-valued Reproducing Kernel Banach Spaces with the $\ell^1$ Norm

Targeting at sparse multi-task learning, we consider regularization models with an $\ell^1$ penalty on the coefficients of kernel functions. In order to provide a kernel method for this model, we construct a class of vector-valued reproducing kernel Banach spaces with the $\ell^1$ norm. The notion of multi-task admissible kernels is proposed so that the constructed spaces could have desirable properties including the crucial linear representer theorem. Such kernels are related to bounded Lebesgue constants of a kernel interpolation question. We study the Lebesgue constant of multi-task kernels…

Mordukhovich导数的一些性质及其在Banach空间局部变分不等式中的应用

Some Properties of Mordukhovich Derivatives with Applications to Locally Variational Inequalities in Banach Spaces

本文研究Banach空间中Frechet导数与Mordukhovich导数的联系，发现集值映射导数性质，引入局部变分不等式概念，并揭示其解与Mordukhovich导数的关联。

Dilations of frames, operator valued measures and bounded linear maps

We will give an outline of the main results in our recent AMS Memoir, and include some new results, exposition and open problems. In that memoir we developed a general dilation theory for operator valued measures acting on Banach spaces where operator-valued measures (or maps) are not necessarily completely bounded. The main results state that any operator-valued measure, not necessarily completely bounded, always has a dilation to a projection-valued measure acting on a Banach space, and every bounded linear map, again not necessarily completely bounded, on a Banach algebra has a bounded homo…

The A_2 theorem and the local oscillation decomposition for Banach space valued functions

We prove that the operator norm of every Banach space valued Calderon-Zygmund operator T on the weighted Lebesgue-Bochner space depends linearly on the Muckenhoupt A_2 characteristic of the weight. In parallel with the proof of the real-valued case, the proof is based on pointwise dominating every Banach space valued Calderon-Zygmund operator by a series of positive dyadic shifts. In common with the real-valued case, the pointwise dyadic domination relies on Lerner's local oscillation decomposition formula, which we extend from real-valued functions to Banach space valued functions. The extens…

2-Normed D-Modules and Hahn-Banach Theorem for D-linear 2-functionals

In this paper we introduce the notion of D-valued 2-norm on hy- perbolic or D-valued modules. Further, we define D-linear 2-functional on these modules and consider some of their properties. We also establish the Hahn- Banach type extension theorem for D-linear 2-functionals.

A Note on Almost Anti-Periodic Functions in Banach Spaces

The main aim of this note is to introduce the notion of an almost anti-periodic function in Banach space. We prove some characterizations for this class of functions, investigating also its relationship with the classes of anti-periodic functions and almost periodic functions in Banach spaces.

带群Lasso范数的向量值再生核巴拿赫空间

Vector-valued Reproducing Kernel Banach Spaces with Group Lasso Norms

该研究为稀疏多任务学习的核方法建立数学基础，构建了带$\ell_{p,1}$群Lasso范数的向量值再生核巴拿赫空间，证明其满足线性表示定理并提出适配的再生核，可用于稀疏多任务学习。

The Daugavet property in spaces of vector-valued Lipschitz functions

We prove that if a metric space $M$ has the finite CEP then $\mathcal F(M)\widehat{\otimes}_π X$ has the Daugavet property for every non-zero Banach space $X$. This applies, for instance, if $M$ is a Banach space whose dual is isometrically an $L_1(μ)$ space. If $M$ has the CEP then $L(\mathcal F(M),X)=\Lip(M,X)$ has the Daugavet property for every non-zero Banach space $X$, showing that this is the case when $M$ is an injective Banach space or a convex subset of a Hilbert space.

Extensions and approximations of Banach-valued Sobolev functions

In complete metric measure spaces equipped with a doubling measure and supporting a weak Poincaré inequality, we investigate when a given Banach-valued Sobolev function defined on a subset satisfying a measure-density condition is the restriction of a Banach-valued Sobolev function defined on the whole space. We investigate the problem for Hajłasz- and Newton-Sobolev spaces, respectively. First, we show that Hajłasz-Sobolev extendability is independent of the target Banach spaces. We also show that every $c_0$-valued Newton-Sobolev extension set is a Banach-valued Newton-Sobolev extension set …

The Banach space -valued BMO, Carleson's condition, and paraproducts

We define a scale of L^q Carleson norms, all of which characterize the membership of a function in BMO. The phenomenon is analogous to the John-Nirenberg inequality, but on the level of Carleson measures. The classical Carleson condition corresponds to the L^2 case in our theory. The result is applied to give a new proof for the L^p-boundedness of paraproducts with a BMO symbol. A novel feature of the argument is that all p are covered at once in a completely interpolation-free manner. This is achieved by using the L^1 Carleson norm, and indicates the usefulness of this notion. Our approach is…

Daugavet property of Banach algebras of holomorphic functions and norm-attaining holomorphic functions

We show that the duals of Banach algebras of scalar-valued bounded holomorphic functions on the open unit ball $B_E$ of a Banach space $E$ lack weak$^*$-strongly exposed points. Consequently, we obtain that some Banach algebras of holomorphic functions on an arbitrary Banach space have the Daugavet property which extends the observation of P. Wojtaszczyk. Moreover, we present a new denseness result by proving that the set of norm-attaining vector-valued holomorphic functions on the open unit ball of a dual Banach space is dense provided that its predual space has the metric $π$-property. Besid…

On certain geometric properties in Banach spaces of vector-valued functions

We consider a certain type of geometric properties of Banach spaces, which includes for instance octahedrality, almost squareness, lushness and the Daugavet property. For this type of properties, we obtain a general reduction theorem, which, roughly speaking, states the following: if the property in question is stable under certain finite absolute sums (for example finite $\ell^p$-sums), then it is also stable under the formation of corresponding Köthe-Bochner spaces (for example $L^p$-Bochner spaces). From this general theorem, we obtain as corollaries a number of new results as well as some …

Vector-valued Reproducing Kernel Banach Spaces with Applications to Multi-task Learning

Motivated by multi-task machine learning with Banach spaces, we propose the notion of vector-valued reproducing kernel Banach spaces (RKBS). Basic properties of the spaces and the associated reproducing kernels are investigated. We also present feature map constructions and several concrete examples of vector-valued RKBS. The theory is then applied to multi-task machine learning. Especially, the representer theorem and characterization equations for the minimizer of regularized learning schemes in vector-valued RKBS are established.

Some Remarks on Vector-Valued Integration

The article presents a new method of integration of functions with values in Banach spaces. This integral and related notions prove to be a useful tool in the study of Banach space geomtry.

$(ω,ρ)$-Periodic solutions of abstract integro-differential impulsive equations on Banach space

In this paper, we investigate the existence and uniqueness of $(ω,ρ)$-periodic solutions for a class of the abstract impulsive integro-differential equations on Banach space.

Banach-valued modulation invariant Carleson embeddings and outer-$L^p$ spaces: the Walsh case

We prove modulation invariant embedding bounds from Bochner spaces $L^p(\mathbb{W};X)$ on the Walsh group to outer-$L^p$ spaces on the Walsh extended phase plane. The Banach space $X$ is assumed to be UMD and sufficiently close to a Hilbert space in an interpolative sense. Our embedding bounds imply $L^p$ bounds and sparse domination for the Banach-valued tritile operator, a discrete model of the Banach-valued bilinear Hilbert transform.

Generic Convergence of Sequences of Successive Approximations in Banach Spaces

We study the generic behavior of the method of successive approximations for set-valued mappings in Banach spaces. We consider, in particular, the case of those set-valued mappings which are defined by pairs of nonexpansive mappings and give a positive answer to a question raised by Francesco S. de Blasi.

Complemented copies of $\ell_1$ in spaces of vector valued measures and applications

Let $X$ be a Banach space and $(Ω,Σ)$ be a measure space. We provide a characterization of sequences in the space of $X$-valued countably additive measures on $Ω,Σ)$ of bounded variation that generate complemented copies of $\ell_1$. As application, we prove that if a dual Banach space $E^*$ has Pełczyński's property (V*) then so does the space of $E^*$-valued countably additive measures with bounded variation. Another application, we show that for a Banach space $X$, the space $\ell_\infty(X)$ contains a complemented copy of $\ell_1$ if and only if $X$ contains all $\ell_1^n$ uniformly comple…

Octahedrality in Lipschitz free Banach spaces

The aim of this note is to study octahedrality in vector valued Lipschitz-free Banach spaces on a metric space under topological hypotheses on it. As a consequence, we get that the space of Lipschitz functions on a metric space valued in a dual Banach space satisfies the weak-star strong diameter two property, under natural topological hipothesess on the metric space. Also, we show an example proving that these hypotheses are optimal.

On Azuma-type inequalities for Banach space-valued martingales

In this paper, we will study concentration inequalities for Banach space-valued martingales. Firstly, we prove that a Banach space $X$ is linearly isomorphic to a $p$-uniformly smooth space ($1<p\leq 2$) if and only if an Azuma-type inequality holds for $X$-valued martingales. This can be viewed as a generalization of Pinelis' work on Azuma inequality for martingales with values in $2$-uniformly smooth space. Secondly, Azuma-type inequality for self-normalized sums will be presented. Finally, some further inequalities for Banach space-valued martingales, such as moment inequalities for double …

Operators on the Banach space of $p$-continuous vector-valued functions

Let $X$, $Y$, and $Z$ be Banach spaces, and let $α$ be a tensor norm. Let a bounded linear operator $S\in\mathcal{L}(Z,\mathcal{L}(X,Y))$ be given. We obtain (necessary and/or sufficient) conditions for the existence of an operator $U\in\mathcal{L}(Z\hat{\otimes}_αX,Y)$ such that $(Sz)x = U(z\otimes x)$, for all $z\in Z$ and $x\in X$, i.e., $S= U^{#}$, the associated operator to $U$. Let $Ω$ be a compact Hausdorff space and denote by $\mathcal{C}(Ω)$ the space of continuous functions from $Ω$ into $\mathbb{K}$. We apply these results to $S\in\mathcal{L}(\mathcal{C}(Ω),\mathcal{L}(X, Y))$ for c…

A note on set-valued Henstock--McShane integral in Banach (lattice) space setting

We study Henstock-type integrals for functions defined in a Radon measure space and taking values in a Banach lattice $X$. Both the single-valued case and the multivalued one are considered (in the last case mainly $cwk(X)$-valued mappings are discussed). The main tool to handle the multivalued case is a Rådström-type embedding theorem established in [50]: in this way we reduce the norm-integral to that of a single-valued function taking values in an $M$-space and we easily obtain new proofs for some decomposition results recently stated in [33,36], based on the existence of integrable selecti…

$L^\infty$ Estimates for the Banach-valued $\bar\partial$ problem in a Disk

We study the differential equation $\frac{\partial G}{\partial\bar z}=g$ with an unbounded Banach-valued Bochner measurable function $g$ on the open unit disk $\mathbb D\subset\mathbb C$. We prove that under some conditions on the growth and essential support of $g$ such equation has a bounded solution given by a continuous linear operator. The obtained results are applicable to the Banach-valued corona problem for the algebra of bounded holomorphic functions on $\mathbb D$ with values in a complex commutative unital Banach algebra.

An Amir-Cambern theorem for subspaces of Banach lattice-valued continuous functions

For $i=1,2$, let $E_i$ be a reflexive Banach lattice over $\mathbb{R}$ with a certain parameter $λ^+(E_i)>1$, let $K_i$ be a locally compact (Hausdorff) topological space and let $\mathcal{H}_i$ be a closed subspace of $\mathcal{C}_0(K_i, E_i)$ such that each point of the Choquet boundary $\mathcal{Ch}_{\mathcal{H}_i} K_i$ of $\mathcal{H}_i$ is a weak peak point. We show that if there exists an isomorphism $T\colon \mathcal{H}_1 \to \mathcal{H}_2$ with $\Vert T \Vert \cdot \Vert T^{-1} \Vert<\min \lbrace λ^+(E_1), λ^+(E_2) \rbrace$ such that $T$ and $T^{-1}$ preserve positivity, then $\mathcal…