Banach Journal of Mathematical Analysis Articles (Project Euclid)
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Note on extreme points in Marcinkiewicz function spaces
http://projecteuclid.org/euclid.bjma/1272374667
<strong> Anna Kaminska </strong>, <strong> Anca M. Parrish </strong><p><strong>Source: </strong>Banach J. Math. Anal., Volume 4, Number 1, 1--12.</p><p><strong>Abstract:</strong><br/>
We show that the unit ball of the subspace $M_W^0$ of ordered continuous
elements of $M_W$ has no extreme points, where $M_W$ is the Marcinkiewicz
function space generated by a decreasing weight function $w$ over the interval
$(0,\infty)$ and $W(t) = \int_0^tw$, $t\in(0,\infty)$. We also present here a
proof of the fact that a function $f$ in the unit ball of $M_W$ is an extreme
point if and only if $f^*=w$.
</p>projecteuclid.org/euclid.bjma/1272374667_Thu, 05 Aug 2010 15:41 EDTThu, 05 Aug 2010 15:41 EDTFrames and representing systems in Fréchet spaces and their dualshttp://projecteuclid.org/euclid.bjma/1476841711<strong>J. Bonet</strong>, <strong>C. Fernández</strong>, <strong>A. Galbis</strong>, <strong>J. M. Ribera</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 1--20.</p><p><strong>Abstract:</strong><br/>
Frames and Bessel sequences in Fréchet spaces and their duals are defined and studied. Their relation with Schauder frames and representing systems is analyzed. The abstract results presented here, when applied to concrete spaces of analytic functions, give examples and consequences about sampling sets and Dirichlet series expansions.
</p>projecteuclid.org/euclid.bjma/1476841711_20161018214836Tue, 18 Oct 2016 21:48 EDTHarmonic analysis on the Proper Velocity gyrogrouphttp://projecteuclid.org/euclid.bjma/1476841712<strong>Milton Ferreira</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 21--49.</p><p><strong>Abstract:</strong><br/>
In this article we study harmonic analysis on the proper velocity (PV) gyrogroup using the gyrolanguage of analytic hyperbolic geometry. This PV addition is the relativistic addition of proper velocities in special relativity, and it is related with the hyperboloid model of hyperbolic geometry. The generalized harmonic analysis depends on a complex parameter $z$ and on the radius $t$ of the hyperboloid, and it comprises the study of the generalized translation operator, the associated convolution operator, the generalized Laplace–Beltrami operator and its eigenfunctions, the generalized Poisson transform and its inverse, the generalized Helgason–Fourier transform and its inverse, and Plancherel’s theorem. In the limit of large $t$ , $t\rightarrow+\infty$ , the generalized harmonic analysis on the hyperboloid tends to the standard Euclidean harmonic analysis on ${\mathbb{R}}^{n}$ , thus unifying hyperbolic and Euclidean harmonic analysis.
</p>projecteuclid.org/euclid.bjma/1476841712_20161018214836Tue, 18 Oct 2016 21:48 EDTAbstract harmonic analysis of wave-packet transforms over locally compact abelian groupshttp://projecteuclid.org/euclid.bjma/1478746986<strong>Arash Ghaani Farashahi</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 50--71.</p><p><strong>Abstract:</strong><br/>
This article presents a systematic study for abstract harmonic analysis aspects of wave-packet transforms over locally compact abelian (LCA) groups. Let $H$ be a locally compact group, let $K$ be an LCA group, and let $\theta:H\to\operatorname{Aut}(K)$ be a continuous homomorphism. We introduce the abstract notion of the wave-packet group generated by $\theta$ , and we study basic properties of wave-packet groups. Then we study theoretical aspects of wave-packet transforms. Finally, we will illustrate application of these techniques in the case of some well-known examples.
</p>projecteuclid.org/euclid.bjma/1478746986_20161109220314Wed, 09 Nov 2016 22:03 ESTDuality for increasing convex functionals with countably many marginal constraintshttp://projecteuclid.org/euclid.bjma/1478746987<strong>Daniel Bartl</strong>, <strong>Patrick Cheridito</strong>, <strong>Michael Kupper</strong>, <strong>Ludovic Tangpi</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 72--89.</p><p><strong>Abstract:</strong><br/>
In this work we derive a convex dual representation for increasing convex functionals on a space of real-valued Borel measurable functions defined on a countable product of metric spaces. Our main assumption is that the functionals fulfill marginal constraints satisfying a certain tightness condition. In the special case where the marginal constraints are given by expectations or maxima of expectations, we obtain linear and sublinear versions of Kantorovich’s transport duality and the recently discovered martingale transport duality on products of countably many metric spaces.
</p>projecteuclid.org/euclid.bjma/1478746987_20161109220314Wed, 09 Nov 2016 22:03 ESTSpaceability in norm-attaining setshttp://projecteuclid.org/euclid.bjma/1478746988<strong>Javier Falcó</strong>, <strong>Domingo García</strong>, <strong>Manuel Maestre</strong>, <strong>Pilar Rueda</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 90--107.</p><p><strong>Abstract:</strong><br/>
We study the existence of infinite-dimensional vector spaces in the sets of norm-attaining operators, multilinear forms, and polynomials. Our main result is that, for every set of permutations $P$ of the set $\{1,\ldots,n\}$ , there exists a closed infinite-dimensional Banach subspace of the space of $n$ -linear forms on $\ell_{1}$ such that, for all nonzero elements $B$ of such a subspace, the Arens extension associated to the permutation $\sigma$ of $B$ is norm-attaining if and only if $\sigma$ is an element of $P$ . We also study the structure of the set of norm-attaining $n$ -linear forms on $c_{0}$ .
</p>projecteuclid.org/euclid.bjma/1478746988_20161109220314Wed, 09 Nov 2016 22:03 ESTDuality for ideals of Lipschitz mapshttp://projecteuclid.org/euclid.bjma/1478746989<strong>M. G. Cabrera-Padilla</strong>, <strong>J. A. Chávez-Domínguez</strong>, <strong>A. Jiménez-Vargas</strong>, <strong>Moisés Villegas-Vallecillos</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 108--129.</p><p><strong>Abstract:</strong><br/>
We develop a systematic approach to the study of ideals of Lipschitz maps from a metric space to a Banach space, inspired by classical theory on using Lipschitz tensor products to relate ideals of operator/tensor norms for Banach spaces. We study spaces of Lipschitz maps from a metric space to a dual Banach space that can be represented canonically as the dual of a Lipschitz tensor product endowed with a Lipschitz cross-norm, and we show that several known examples of ideals of Lipschitz maps (Lipschitz maps, Lipschitz $p$ -summing maps, maps admitting Lipschitz factorization through subsets of $L_{p}$ -space) admit such a representation. Generally, we characterize when the space of a Lipschitz map from a metric space to a dual Banach space is in canonical duality with a Lipschitz cross-norm. Finally, we introduce a concept of operators which are approximable with respect to one of these ideals of Lipschitz maps, and we identify them in terms of tensor-product notions.
</p>projecteuclid.org/euclid.bjma/1478746989_20161109220314Wed, 09 Nov 2016 22:03 ESTHlawka’s functional inequality on topological groupshttp://projecteuclid.org/euclid.bjma/1480474816<strong>Włodzimierz Fechner</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 130--142.</p><p><strong>Abstract:</strong><br/>
Let $(X,+)$ be a topological abelian group. We discuss regularity of solutions $f\colon X\to\mathbb{R}$ of Hlawka’s functional inequality
\[f(x+y)+f(y+z)+f(x+z)\leq f(x+y+z)+f(x)+f(y)+f(z),\] postulated for all $x,y,z\in X$ . We study the lower and upper hull of $f$ . Moreover, we provide conditions which imply continuity of $f$ . We prove, in particular, that if $X$ is generated by any neighborhood of zero, $f$ is continuous at zero, and $f(0)=0$ , then $f$ is continuous on $X$ .
</p>projecteuclid.org/euclid.bjma/1480474816_20161129220026Tue, 29 Nov 2016 22:00 ESTApproximative compactness in Musielak–Orlicz function spaces of Bochner typehttp://projecteuclid.org/euclid.bjma/1480474817<strong>Shaoqiang Shang</strong>, <strong>Yunan Cui</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 143--163.</p><p><strong>Abstract:</strong><br/>
In this article, we give the criteria for approximative compactness of every proximinal convex subset of Musielak–Orlicz–Bochner function spaces equipped with the Orlicz norm. As a corollary, we give the criteria for approximative compactness of Musielak–Orlicz–Bochner function spaces equipped with the Orlicz norm.
</p>projecteuclid.org/euclid.bjma/1480474817_20161129220026Tue, 29 Nov 2016 22:00 ESTUnbounded composition operators via inductive limits: Cosubnormal operators with matrix symbols, IIhttp://projecteuclid.org/euclid.bjma/1480474818<strong>Piotr Budzyński</strong>, <strong>Piotr Dymek</strong>, <strong>Artur Płaneta</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 164--187.</p><p><strong>Abstract:</strong><br/>
This article deals with unbounded composition operators with infinite matrix symbols acting in $L^{2}$ -spaces with respect to the Gaussian measure on $\mathbb{R}^{\infty}$ . We introduce weak cohyponormality classes $\mathcal{S}_{n,r}^{*}$ of unbounded operators and provide criteria for the aforementioned composition operators to belong to $\mathcal{S}_{n,r}^{*}$ . Our approach is based on inductive limits of operators.
</p>projecteuclid.org/euclid.bjma/1480474818_20161129220026Tue, 29 Nov 2016 22:00 EST$\ell_{p}$ -maximal regularity for a class of fractional difference equations on UMD spaces: The case $1\lt \alpha\leq2$http://projecteuclid.org/euclid.bjma/1480474819<strong>Carlos Lizama</strong>, <strong>Marina Murillo-Arcila</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 188--206.</p><p><strong>Abstract:</strong><br/>
By using Blunck’s operator-valued Fourier multiplier theorem, we completely characterize the existence and uniqueness of solutions in Lebesgue sequence spaces for a discrete version of the Cauchy problem with fractional order $1\lt \alpha\leq2$ . This characterization is given solely in spectral terms on the data of the problem, whenever the underlying Banach space belongs to the UMD-class.
</p>projecteuclid.org/euclid.bjma/1480474819_20161129220026Tue, 29 Nov 2016 22:00 ESTOrder structure, multipliers, and Gelfand representation of vector-valued function algebrashttp://projecteuclid.org/euclid.bjma/1481274115<strong>Jorma Arhippainen</strong>, <strong>Jukka Kauppi</strong>, <strong>Jussi Mattas</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 207--222.</p><p><strong>Abstract:</strong><br/>
We continue the study begun by the third author of $C^{*}$ -Segal algebra-valued function algebras with an emphasis on the order structure. Our main result is a characterization theorem for $C^{*}$ -Segal algebra-valued function algebras with an order unitization. As an intermediate step, we establish a function algebraic description of the multiplier module of arbitrary Segal algebra-valued function algebras. We also consider the Gelfand representation of these algebras in the commutative case.
</p>projecteuclid.org/euclid.bjma/1481274115_20161209040212Fri, 09 Dec 2016 04:02 ESTTriangular summability and Lebesgue points of $2$ -dimensional Fourier transformshttp://projecteuclid.org/euclid.bjma/1481274116<strong>Ferenc Weisz</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 1, 223--238.</p><p><strong>Abstract:</strong><br/>
We consider the triangular $\theta$ -summability of $2$ -dimensional Fourier transforms. Under some conditions on $\theta$ , we show that the triangular $\theta$ -means of a function $f$ belonging to the Wiener amalgam space $W(L_{1},\ell_{\infty})({\mathbb{R}}^{2})$ converge to $f$ at each modified strong Lebesgue point. The same holds for a weaker version of Lebesgue points for the so-called modified Lebesgue points of $f\in W(L_{p},\ell_{\infty})({\mathbb{R}}^{2})$ whenever $1\lt p\lt \infty$ . Some special cases of the $\theta$ -summation are considered, such as the Weierstrass, Abel, Picard, Bessel, Fejér, de La Vallée-Poussin, Rogosinski, and Riesz summations.
</p>projecteuclid.org/euclid.bjma/1481274116_20161209040212Fri, 09 Dec 2016 04:02 ESTErgodic behaviors of the regular operator meanshttp://projecteuclid.org/euclid.bjma/1484363107<strong>Laurian Suciu</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 239--265.</p><p><strong>Abstract:</strong><br/>
This article deals with some ergodic properties for general sequences in the closed convex hull of the orbit of some (not necessarily power-bounded) operators in Banach spaces. A regularity condition more general than that of ergodicity is used to obtain some versions of the Esterle–Katznelson–Tzafriri theorem. Also, the ergodicity of the backward iterates of a sequence is proved under appropriate assumptions as, for example, its peripheral boundedness on the unit circle. The applications concern uniformly Kreiss-bounded operators, and other ergodic results are obtained for the binomial means and some operator means related to the Cesàro means.
</p>projecteuclid.org/euclid.bjma/1484363107_20170113220512Fri, 13 Jan 2017 22:05 ESTExtended spectrum and extended eigenspaces of quasinormal operatorshttp://projecteuclid.org/euclid.bjma/1484363108<strong>Gilles Cassier</strong>, <strong>Hasan Alkanjo</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 266--281.</p><p><strong>Abstract:</strong><br/>
We say that a complex number $\lambda$ is an extended eigenvalue of a bounded linear operator $T$ on a Hilbert space $\mathcal{H}$ if there exists a nonzero bounded linear operator $X$ acting on $\mathcal{H}$ , called the extended eigenvector associated to $\lambda$ , and satisfying the equation $TX=\lambda XT$ . In this article, we describe the sets of extended eigenvalues and extended eigenvectors for the quasinormal operators.
</p>projecteuclid.org/euclid.bjma/1484363108_20170113220512Fri, 13 Jan 2017 22:05 ESTOn Cohomology for Product Systemshttp://projecteuclid.org/euclid.bjma/1484816415<strong>Jeong Hee Hong</strong>, <strong>Mi Jung Son</strong>, <strong>Wojciech Szymański</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 282--294.</p><p><strong>Abstract:</strong><br/>
A cohomology for product systems of Hilbert bimodules is defined via the $\operatorname{Ext}$ functor. For the class of product systems corresponding to irreversible algebraic dynamics, relevant resolutions are found explicitly and it is shown how the underlying product system can be twisted by 2-cocycles. In particular, this process gives rise to cohomological deformations of the $C^{*}$ -algebras associated with the product system. Concrete examples of deformations of the Cuntz’s algebra ${\mathcal{Q}}_{\mathbb{N}}$ arising this way are investigated, and we show that they are simple and purely infinite.
</p>projecteuclid.org/euclid.bjma/1484816415_20170119040053Thu, 19 Jan 2017 04:00 ESTThe approximate hyperplane series property and related propertieshttp://projecteuclid.org/euclid.bjma/1484816416<strong>María D. Acosta</strong>, <strong>Richard Martin Aron</strong>, <strong>Francisco Javier García-Pacheco</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 295--310.</p><p><strong>Abstract:</strong><br/>
We show that the approximate hyperplane series property consequence, we obtain that the class of spaces $Y$ such that the pair $(\ell_{1},Y)$ has the Bishop–Phelps–Bollobás property for operators is stable under finite $\ell_{p}$ -sums for $1\leq p\lt \infty$ . We also deduce that every Banach space of dimension at least $2$ can be equivalently renormed to have the AHSp but to fail Lindenstrauss’ property $\beta$ . We also show that every infinite-dimensional Banach space admitting an equivalent strictly convex norm also admits such an equivalent norm failing the AHSp.
</p>projecteuclid.org/euclid.bjma/1484816416_20170119040053Thu, 19 Jan 2017 04:00 ESTComposition operators on the Bloch space of the unit ball of a Hilbert spacehttp://projecteuclid.org/euclid.bjma/1485572420<strong>Oscar Blasco</strong>, <strong>Pablo Galindo</strong>, <strong>Mikael Lindström</strong>, <strong>Alejandro Miralles</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 311--334.</p><p><strong>Abstract:</strong><br/>
Every analytic self-map of the unit ball of a Hilbert space induces a bounded composition operator on the space of Bloch functions. Necessary and sufficient conditions for compactness of such composition operators are provided, as well as some examples that clarify the connections among such conditions.
</p>projecteuclid.org/euclid.bjma/1485572420_20170127220034Fri, 27 Jan 2017 22:00 ESTNorm estimates for random polynomials on the scale of Orlicz spaceshttp://projecteuclid.org/euclid.bjma/1485572421<strong>Andreas Defant</strong>, <strong>Mieczysław Mastyło</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 335--347.</p><p><strong>Abstract:</strong><br/>
We prove an upper bound for the supremum norm of homogeneous Bernoulli polynomials on the unit ball of finite-dimensional complex Banach spaces. This result is inspired by the famous Kahane–Salem–Zygmund inequality and its recent extensions; in contrast to the known results, our estimates are on the scale of Orlicz spaces instead of $\ell_{p}$ -spaces. Applications are given to multidimensional Bohr radii for holomorphic functions in several complex variables, and to the study of unconditionality of spaces of homogenous polynomials in Banach spaces.
</p>projecteuclid.org/euclid.bjma/1485572421_20170127220034Fri, 27 Jan 2017 22:00 ESTNew results on Kottman’s constanthttp://projecteuclid.org/euclid.bjma/1487732418<strong>Jesús M. F. Castillo</strong>, <strong>Manuel González</strong>, <strong>Pier Luigi Papini</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 348--362.</p><p><strong>Abstract:</strong><br/>
We present new results on Kottman’s constant of a Banach space, showing (i) that every Banach space is isometric to a hyperplane of a Banach space having Kottman’s constant 2 and (ii) that Kottman’s constant of a Banach space and of its bidual can be different. We say that a Banach space is a Diestel space if the infimum of Kottman’s constants of its subspaces is greater that 1. We show that every Banach space contains a Diestel subspace and that minimal Banach spaces are Diestel spaces.
</p>projecteuclid.org/euclid.bjma/1487732418_20170221220035Tue, 21 Feb 2017 22:00 ESTRadon–Nikodym theorems for operator-valued measures and continuous generalized frameshttp://projecteuclid.org/euclid.bjma/1487732419<strong>Fengjie Li</strong>, <strong>Pengtong Li</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 363--381.</p><p><strong>Abstract:</strong><br/>
In this article we determine that an operator-valued measure (OVM) for Banach spaces is actually a weak∗ measure, and then we show that an OVM can be represented as an operator-valued function if and only if it has $\sigma$ -finite variation. By the means of direct integrals of Hilbert spaces, we introduce and investigate continuous generalized frames ( continuous operator-valued frames , or simply CG frames ) for general Hilbert spaces. It is shown that there exists an intrinsic connection between CG frames and positive OVMs. As a byproduct, we show that a Riesz-type CG frame does not exist unless the associated measure space is purely atomic. Also, a dilation theorem for dual pairs of CG frames is given.
</p>projecteuclid.org/euclid.bjma/1487732419_20170221220035Tue, 21 Feb 2017 22:00 ESTOn a generalized Šemrl’s theorem for weak 2-local derivations on $B(H)$http://projecteuclid.org/euclid.bjma/1488877211<strong>Juan Carlos Cabello</strong>, <strong>Antonio M. Peralta</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 382--397.</p><p><strong>Abstract:</strong><br/>
We prove that, for every complex Hilbert space $H$ , every weak 2-local derivation on $B(H)$ or on $K(H)$ is a linear derivation. We also establish that every weak 2-local derivation on an atomic von Neumann algebra or on a compact C $^{*}$ -algebra is a linear derivation.
</p>projecteuclid.org/euclid.bjma/1488877211_20170307040039Tue, 07 Mar 2017 04:00 ESTLattice properties of the core-partial orderhttp://projecteuclid.org/euclid.bjma/1488877212<strong>Marko S. Djikić</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 398--415.</p><p><strong>Abstract:</strong><br/>
We show that in an arbitrary Hilbert space, the set of group-invertible operators with respect to the core-partial order has the complete lower semilattice structure, meaning that an arbitrary family of operators possesses the core-infimum. We also give a necessary and sufficient condition for the existence of the core-supremum of an arbitrary family, and we study the properties of these lattice operations on pairs of operators.
</p>projecteuclid.org/euclid.bjma/1488877212_20170307040039Tue, 07 Mar 2017 04:00 ESTAdditive maps preserving Drazin invertible operators of index $n$http://projecteuclid.org/euclid.bjma/1489802494<strong>Mostafa Mbekhta</strong>, <strong>Mourad Oudghiri</strong>, <strong>Khalid Souilah</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 416--437.</p><p><strong>Abstract:</strong><br/>
Given an integer $n\geq2$ , in this article we provide a complete description of all additive surjective maps on the algebra of all bounded linear operators acting on an infinite-dimensional complex Banach space, preserving in both directions the set of Drazin invertible operators of index $n$ .
</p>projecteuclid.org/euclid.bjma/1489802494_20170317220159Fri, 17 Mar 2017 22:01 EDTOn some Hardy-type inequalities for fractional calculus operatorshttp://projecteuclid.org/euclid.bjma/1489802495<strong>Sajid Iqbal</strong>, <strong>Josip Pečarić</strong>, <strong>Muhammad Samraiz</strong>, <strong>Zivorad Tomovski</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 2, 438--457.</p><p><strong>Abstract:</strong><br/>
In this article we present applications of Hardy-type and refined Hardy-type inequalities for a generalized fractional integral operator involving the Mittag-Leffler function in its kernel and for the Hilfer fractional derivative using convex and monotone convex functions.
</p>projecteuclid.org/euclid.bjma/1489802495_20170317220159Fri, 17 Mar 2017 22:01 EDTDisjoint hypercyclic weighted translations on groupshttp://projecteuclid.org/euclid.bjma/1492618124<strong>Chung-Chuan Chen</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 459--476.</p><p><strong>Abstract:</strong><br/>
Let $1\leq p\lt \infty$ , and let $G$ be a locally compact group. We characterize disjoint hypercyclic weighted translation operators on the Lebesgue space $L^{p}(G)$ in terms of the weight, the Haar measure, and the group element. Disjoint supercyclic, disjoint mixing, and dual disjoint hypercyclic weighted translation operators are also characterized.
</p>projecteuclid.org/euclid.bjma/1492618124_20170718220400Tue, 18 Jul 2017 22:04 EDTHardy-type space estimates for multilinear commutators of Calderón–Zygmund operators on nonhomogeneous metric measure spaceshttp://projecteuclid.org/euclid.bjma/1492618125<strong>Jie Chen</strong>, <strong>Haibo Lin</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 477--496.</p><p><strong>Abstract:</strong><br/>
Let $(\mathcal{X},d,\mu)$ be a metric measure space satisfying the so-called upper doubling condition and the geometrically doubling condition . Let $T$ be a Calderón–Zygmund operator and let $\vec{b}:=(b_{1},\ldots,b_{m})$ be a finite family of $\operatorname{\widetilde{RBMO}}(\mu)$ functions. In this article, the authors establish the boundedness of the multilinear commutator $T_{\vec{b}}$ , generated by $T$ and $\vec{b}$ from the atomic Hardy-type space $\widetilde{H}_{\mathrm{fin},\vec{b},m,\rho}^{1,q,m+1}(\mu)$ into the Lebesgue space $L^{1}(\mu)$ . The authors also prove that $T_{\vec{b}}$ is bounded from the atomic Hardy-type space $\widetilde{H}_{\mathrm{fin},\vec{b},m,\rho}^{1,q,m+2}(\mu)$ into the atomic Hardy space $\widetilde{H}^{1}(\mu)$ via the molecular characterization of $\widetilde{H}^{1}(\mu)$ .
</p>projecteuclid.org/euclid.bjma/1492618125_20170718220400Tue, 18 Jul 2017 22:04 EDTOn the existence of at least a solution for functional integral equations via measure of noncompactnesshttp://projecteuclid.org/euclid.bjma/1492618126<strong>Calogero Vetro</strong>, <strong>Francesca Vetro</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 497--512.</p><p><strong>Abstract:</strong><br/>
In this article, we use fixed-point methods and measure of noncompactness theory to focus on the problem of establishing the existence of at least a solution for the following functional integral equation
\[u(t)=g(t,u(t))+\int_{0}^{t}G(t,s,u(s))\,ds,\quad t\in{[0,+\infty[},\] in the space of all bounded and continuous real functions on $\mathbb{R}_{+}$ , under suitable assumptions on $g$ and $G$ . Also, we establish an extension of Darbo’s fixed-point theorem and discuss some consequences.
</p>projecteuclid.org/euclid.bjma/1492618126_20170718220400Tue, 18 Jul 2017 22:04 EDTWeighted Herz space estimates for Hausdorff operators on the Heisenberg grouphttp://projecteuclid.org/euclid.bjma/1492618127<strong>Jianmiao Ruan</strong>, <strong>Dashan Fan</strong>, <strong>Qingyan Wu</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 513--535.</p><p><strong>Abstract:</strong><br/>
In this article, we study the Hausdorff operator, defined via a general linear mapping $A$ , on weighted Herz spaces in the setting of the Heisenberg group. Under some assumptions on the mapping $A$ , we establish its sharp boundedness on power-weighted Herz spaces and power-weighted Lebesgue spaces in the Heisenberg group. Our proof is heavily based on the block decomposition of the Herz space, which is quite different from any other function spaces. Our results extend and improve some existing theorems.
</p>projecteuclid.org/euclid.bjma/1492618127_20170718220400Tue, 18 Jul 2017 22:04 EDTToeplitz algebras arising from escape points of interval mapshttp://projecteuclid.org/euclid.bjma/1493431219<strong>C. Correia Ramos</strong>, <strong>Nuno Martins</strong>, <strong>Paulo R. Pinto</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 536--553.</p><p><strong>Abstract:</strong><br/>
We generate a representation of the Toeplitz $C^{\ast}$ -algebra $\mathcal{T}_{A_{f}}$ on a Hilbert space $H_{x}$ that encodes the orbit of an escape point $x\in I$ of a Markov interval map $f$ , with transition matrix $A_{f}$ . This leads to a family of representations of $\mathcal{T}_{A_{f}}$ labeled by points in all intervals $I$ . The underlying dynamics of the interval map are used in the study of this family.
</p>projecteuclid.org/euclid.bjma/1493431219_20170718220400Tue, 18 Jul 2017 22:04 EDTTwo-sided and one-sided invertibility of Wiener-type functional operators with a shift and slowly oscillating datahttp://projecteuclid.org/euclid.bjma/1493776976<strong>Gustavo Fernández-Torres</strong>, <strong>Yuri Karlovich</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 554--590.</p><p><strong>Abstract:</strong><br/>
Let $\alpha$ be an orientation-preserving homeomorphism of $[0,\infty]$ onto itself with only two fixed points at $0$ and $\infty$ , whose restriction to $\mathbb{R}_{+}=(0,\infty)$ is a diffeomorphism, and let $U_{\alpha}$ be the isometric shift operator acting on the Lebesgue space $L^{p}(\mathbb{R}_{+})$ with $p\in[1,\infty]$ by the rule $U_{\alpha}f=(\alpha')^{1/p}(f\circ\alpha)$ . We establish criteria of the two-sided and one-sided invertibility of functional operators of the form \begin{equation}A=\sum_{k\in\mathbb{Z}}a_{k}U_{\alpha}^{k}\quadwhere\Vert A\Vert _{W}=\sum_{k\in\mathbb{Z}}\Vert a_{k}\Vert _{L^{\infty}(\mathbb{R}_{+})}\lt \infty,\end{equation} on the spaces $L^{p}(\mathbb{R}_{+})$ under the assumptions that the functions $\log\alpha'$ and $a_{k}$ for all $k\in\mathbb{Z}$ are bounded and continuous on $\mathbb{R}_{+}$ and may have slowly oscillating discontinuities at $0$ and $\infty$ . The unital Banach algebra $\mathfrak{A}_{W}$ of such operators is inverse-closed: if $A\in\mathfrak{A}_{W}$ is invertible on $L^{p}(\mathbb{R}_{+})$ for $p\in[1,\infty]$ , then $A^{-1}\in\mathfrak{A}_{W}$ . Obtained criteria are of two types: in terms of the two-sided or one-sided invertibility of so-called discrete operators on the spaces $l^{p}$ and in terms of conditions related to the fixed points of $\alpha$ and the orbits $\{\alpha^{n}(t):n\in\mathbb{Z}\}$ of points $t\in\mathbb{R}_{+}$ .
</p>projecteuclid.org/euclid.bjma/1493776976_20170718220400Tue, 18 Jul 2017 22:04 EDTA generalization of Kantorovich operators for convex compact subsetshttp://projecteuclid.org/euclid.bjma/1494036023<strong>Francesco Altomare</strong>, <strong>Mirella Cappelletti Montano</strong>, <strong>Vita Leonessa</strong>, <strong>Ioan Raşa</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 591--614.</p><p><strong>Abstract:</strong><br/>
In this article, we introduce and study a new sequence of positive linear operators acting on function spaces defined on a convex compact subset. Their construction depends on a given Markov operator, a positive real number, and a sequence of Borel probability measures. By considering special cases of these parameters for particular convex compact subsets, we obtain the classical Kantorovich operators defined in the $1$ -dimensional and multidimensional setting together with several of their wide-ranging generalizations scattered in the literature. We investigate the approximation properties of these operators by also providing several estimates of the rate of convergence. Finally, we discuss the preservation of Lipschitz-continuity and of convexity.
</p>projecteuclid.org/euclid.bjma/1494036023_20170718220400Tue, 18 Jul 2017 22:04 EDTThe multiplier algebra of the noncommutative Schwartz spacehttp://projecteuclid.org/euclid.bjma/1494036021<strong>Tomasz Ciaś</strong>, <strong>Krzysztof Piszczek</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 615--635.</p><p><strong>Abstract:</strong><br/>
We describe the multiplier algebra of the noncommutative Schwartz space. This multiplier algebra can be seen as the largest $^{*}$ -algebra of unbounded operators on a separable Hilbert space with the classical Schwartz space of rapidly decreasing functions as the domain. We show in particular that it is neither a $\mathcal{Q}$ -algebra nor $m$ -convex. On the other hand, we prove that classical tools of functional analysis, for example, the closed graph theorem, the open mapping theorem, or the uniform boundedness principle, are still available.
</p>projecteuclid.org/euclid.bjma/1494036021_20170718220400Tue, 18 Jul 2017 22:04 EDTNormed Orlicz function spaces which can be quasi-renormed with easily calculable quasinormshttp://projecteuclid.org/euclid.bjma/1496973700<strong>Paweł Foralewski</strong>, <strong>Henryk Hudzik</strong>, <strong>Radosław Kaczmarek</strong>, <strong>Miroslav Krbec</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 636--660.</p><p><strong>Abstract:</strong><br/>
We are interested in the widest possible class of Orlicz functions $\Phi$ such that the easily calculable quasinorm $[f]_{\Phi,p}:=\Vert f\Vert_{E}\{I_{\Phi}(\frac{f}{\Vertf\Vert_{E}})\}^{1\slash p}$ if $f\neq0$ and $[f]_{\Phi,p}=0$ if $f=0$ , on the Orlicz space $L^{\Phi}(\Omega,\Sigma,\mu)$ generated by $\Phi$ , is equivalent to the Luxemburg norm $\Vert\cdot\Vert_{\Phi}$ . To do this, we use a suitable $\Delta_{2}$ -condition, lower and upper Simonenko indices $p_{S}^{a}(\Phi)$ and $q_{S}^{a}(\Phi)$ for the generating function $\Phi$ , numbers $p\in[1,p_{S}^{a}(\Phi)]$ satisfying $q_{S}^{a}(\Phi)-p\leq1$ , and an embedding of $L^{\Phi}(\Omega,\Sigma,\mu)$ into a suitable Köthe function space $E=E(\Omega,\Sigma,\mu)$ . We take as $E$ the Lebesgue spaces $L^{r}(\Omega,\Sigma,\mu)$ with $r\in[1,p_{S}^{l}(\Phi)]$ , when the measure $\mu$ is nonatomic and finite, and the weighted Lebesgue spaces $L^{r}_{\omega}(\Omega,\Sigma,\mu)$ , with $r\in[1,p_{S}^{a}(\Phi)]$ and a suitable weight function $\omega$ , when the measure $\mu$ is nonatomic infinite but $\sigma$ -finite. We also use condition $\nabla_{3}$ if $p_{S}^{a}(\Phi)=1$ and condition $\nabla^{2}$ if $p_{S}^{a}(\Phi)\gt 1$ , proving their necessity in most of the considered cases. Our results seem important for applications of Orlicz function spaces.
</p>projecteuclid.org/euclid.bjma/1496973700_20170718220400Tue, 18 Jul 2017 22:04 EDTA hybrid shrinking projection method for common fixed points of a finite family of demicontractive mappings with variational inequality problemshttp://projecteuclid.org/euclid.bjma/1495505201<strong>Suthep Suantai</strong>, <strong>Withun Phuengrattana</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 661--675.</p><p><strong>Abstract:</strong><br/>
In this article, we prove some properties of a demicontractive mapping defined on a nonempty closed convex subset of a Hilbert space. By using these properties, we obtain strong convergence theorems of a hybrid shrinking projection method for finding a common element of the set of common fixed points of a finite family of demicontractive mappings and the set of common solutions of a finite family of variational inequality problems in a Hilbert space. A numerical example is presented to illustrate the proposed method and convergence result. Our results improve and extend the corresponding results existing in the literature.
</p>projecteuclid.org/euclid.bjma/1495505201_20170718220400Tue, 18 Jul 2017 22:04 EDTTernary weak amenability of the bidual of a JB $^{*}$ -triplehttp://projecteuclid.org/euclid.bjma/1496973699<strong>Mohsen Niazi</strong>, <strong>Mohammad Reza Miri</strong>, <strong>Hamid Reza Ebrahimi Vishki</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 676--697.</p><p><strong>Abstract:</strong><br/>
Beside the triple product induced by ultrapowers on the bidual of a JB $^{*}$ -triple, we assign a triple product to the bidual, $E^{**}$ , of a JB-triple system $E$ , and we show that, under some mild conditions, it makes $E^{**}$ a JB-triple system. To study ternary $n$ -weak amenability of $E^{**}$ , we need to improve the module structures in the category of JB-triple systems and their iterated duals, which lead us to introduce a new type of ternary module. We then focus on the main question: when does ternary $n$ -weak amenability of $E^{**}$ imply the same property for $E?$ In this respect, we show that if the bidual of a JB $^{*}$ -triple $E$ is ternary $n$ -weakly amenable, then $E$ is ternary $n$ -quasiweakly amenable. However, for a general JB-triple system, the results are slightly different for $n=1$ and $n\geq2$ , and the case $n=1$ requires some additional assumptions.
</p>projecteuclid.org/euclid.bjma/1496973699_20170718220400Tue, 18 Jul 2017 22:04 EDTOn the universal and strong $(L^{1},L^{\infty})$ -property related to Fourier–Walsh serieshttp://projecteuclid.org/euclid.bjma/1494900292<strong>Martin G. Grigoryan</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 3, 698--712.</p><p><strong>Abstract:</strong><br/>
In this article, we construct a function $U\in L^{1}[0,1)$ with strictly decreasing Fourier–Walsh coefficients $\{c_{k}(U)\}\searrow$ , and having a universal and strong $(L^{1},L^{\infty})$ -property with respect to the Walsh system.
</p>projecteuclid.org/euclid.bjma/1494900292_20170718220400Tue, 18 Jul 2017 22:04 EDTFourier multiplier theorems on Besov spaces under type and cotype conditionshttps://projecteuclid.org/euclid.bjma/1495094417<strong>Jan Rozendaal</strong>, <strong>Mark Veraar</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 713--743.</p><p><strong>Abstract:</strong><br/>
In this article, we consider Fourier multiplier operators between vector-valued Besov spaces with different integrability exponents $p$ and $q$ , which depend on the type $p$ and cotype $q$ of the underlying Banach spaces. In a previous article, we considered $L^{p}$ - $L^{q}$ multiplier theorems. In the current article, we show that in the Besov scale one can obtain results with optimal integrability exponents. Moreover, we derive a sharp result in the $L^{p}$ - $L^{q}$ setting as well.
We consider operator-valued multipliers without smoothness assumptions. The results are based on a Fourier multiplier theorem for functions with compact Fourier support. If the multiplier has smoothness properties, then the boundedness of the multiplier operator extrapolates to other values of $p$ and $q$ for which $\frac{1}{p}-\frac{1}{q}$ remains constant.
</p>projecteuclid.org/euclid.bjma/1495094417_20171004220208Wed, 04 Oct 2017 22:02 EDTMaps preserving a new version of quantum $f$ -divergencehttps://projecteuclid.org/euclid.bjma/1498097003<strong>Marcell Gaál</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 744--763.</p><p><strong>Abstract:</strong><br/>
For an arbitrary nonaffine operator convex function defined on the nonnegative real line and satisfying $f(0)=0$ , we characterize the bijective maps on the set of all positive definite operators preserving a new version of quantum $f$ -divergence. We also determine the structure of all transformations leaving this quantity invariant on quantum states for any strictly convex functions with the properties $f(0)=0$ and $\lim_{x\to\infty}f(x)/x=\infty$ . Finally, we derive the corresponding result concerning those transformations on the set of positive semidefinite operators. We emphasize that all the results are obtained for finite-dimensional Hilbert spaces.
</p>projecteuclid.org/euclid.bjma/1498097003_20171004220208Wed, 04 Oct 2017 22:02 EDTLimit dynamical systems and $C^{*}$ -algebras from self-similar graph actionshttps://projecteuclid.org/euclid.bjma/1498118444<strong>Inhyeop Yi</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 764--784.</p><p><strong>Abstract:</strong><br/>
In this article, we study dynamical and $C^{*}$ -algebraic properties of self-similar group actions on finite directed graphs. We investigate the structure of limit dynamical systems induced from group actions on graphs, and we deduce conditions of group actions and graphs for the groupoid $C^{*}$ -algebras defined by limit dynamical systems to be simple, separable, purely infinite, nuclear, and satisfying the universal coefficient theorem.
</p>projecteuclid.org/euclid.bjma/1498118444_20171004220208Wed, 04 Oct 2017 22:02 EDTAnalytic Fourier–Feynman transforms and convolution products associated with Gaussian processes on Wiener spacehttps://projecteuclid.org/euclid.bjma/1498809807<strong>Seung Jun Chang</strong>, <strong>Jae Gil Choi</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 785--807.</p><p><strong>Abstract:</strong><br/>
Using Gaussian processes, we define a very general convolution product of functionals on Wiener space and we investigate fundamental relationships between the generalized Fourier–Feynman transforms and the generalized convolution products. Using two rotation theorems of Gaussian processes, we establish that both of the generalized Fourier–Feynman transform of the generalized convolution product and the generalized convolution product of the generalized Fourier–Feynman transforms of functionals on Wiener space are represented as products of the generalized Fourier–Feynman transforms of each functional, with examples.
</p>projecteuclid.org/euclid.bjma/1498809807_20171004220208Wed, 04 Oct 2017 22:02 EDTSine and cosine equations on hypergroupshttps://projecteuclid.org/euclid.bjma/1498809806<strong>Żywilla Fechner</strong>, <strong>László Székelyhidi</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 808--824.</p><p><strong>Abstract:</strong><br/>
This article deals with trigonometric functional equations on hypergroups. We describe the general continuous solution of sine and cosine addition formulas and a so-called sine-cosine functional equation on a locally compact hypergroup in terms of exponential functions, sine functions, and second-order generalized moment functions.
</p>projecteuclid.org/euclid.bjma/1498809806_20171004220208Wed, 04 Oct 2017 22:02 EDTOn the composition ideals of Lipschitz mappingshttps://projecteuclid.org/euclid.bjma/1502935412<strong>Khalil Saadi</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 825--840.</p><p><strong>Abstract:</strong><br/>
We study some properties of Lipschitz mappings which admit factorization through an operator ideal. Lipschitz cross norms have been established from known tensor norms in order to represent certain classes of Lipschitz mappings. Inspired by the definition of $p$ -summing linear operators, we derive a new class of Lipschitz mappings that is called strictly Lipschitz $p$ -summing .
</p>projecteuclid.org/euclid.bjma/1502935412_20171004220208Wed, 04 Oct 2017 22:02 EDTTent spaces at endpointshttps://projecteuclid.org/euclid.bjma/1502935413<strong>Yong Ding</strong>, <strong>Ting Mei</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 841--863.</p><p><strong>Abstract:</strong><br/>
In 1985, Coifman, Meyer, and Stein gave the duality of the tent spaces; that is, $(T_{q}^{p}(\mathbb{R}^{n+1}_{+}))^{\ast}=T_{q'}^{p'}(\mathbb{R}^{n+1}_{+})$ for $1\lt p,q\lt \infty$ , and $(T_{\infty}^{1}(\mathbb{R}^{n+1}_{+}))^{\ast}=\mathscr{C}(\mathbb{R}^{n+1}_{+})$ , $(T_{q}^{1}(\mathbb{R}^{n+1}_{+}))^{\ast}=T_{q'}^{\infty}(\mathbb{R}^{n+1}_{+})$ for $1\lt q\lt \infty$ , where $\mathscr{C}(\mathbb{R}^{n+1}_{+})$ denotes the Carleson measure space on $\mathbb{R}^{n+1}_{+}$ . We prove that $(\mathscr{C}_{v}(\mathbb{R}^{n+1}_{+}))^{\ast}=T_{\infty}^{1}(\mathbb{R}^{n+1}_{+})$ , which we introduced recently, where $\mathscr{C}_{v}(\mathbb{R}^{n+1}_{+})$ is the vanishing Carleson measure space on $\mathbb{R}^{n+1}_{+}$ . We also give the characterizations of $T_{q}^{\infty}(\mathbb{R}^{n+1}_{+})$ by the boundedness of the Poisson integral. As application, we give the boundedness and compactness on $L^{q}(\mathbb{R}^{n})$ of the paraproduct $\pi_{F}$ associated with the tent space $T_{q}^{\infty}(\mathbb{R}^{n+1}_{+})$ , and we extend partially an interesting result given by Coifman, Meyer, and Stein, which establishes a close connection between the tent spaces $T_{2}^{p}(\mathbb{R}^{n+1}_{+})$ $(1\le p\le\infty)$ and $L^{p}(\mathbb{R}^{n})$ , $H^{p}(\mathbb{R}^{n})$ and $\mathit{BMO}(\mathbb{R}^{n})$ spaces.
</p>projecteuclid.org/euclid.bjma/1502935413_20171004220208Wed, 04 Oct 2017 22:02 EDTPoint multipliers and the Gleason–Kahane–Żelazko theoremhttps://projecteuclid.org/euclid.bjma/1502935411<strong>Razieh Sadat Ghodrat</strong>, <strong>Fereshteh Sady</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 864--879.</p><p><strong>Abstract:</strong><br/>
Let $A$ be a Banach algebra, and let $\mathcal{X}$ be a left Banach $A$ -module. In this paper, using the notation of point multipliers on left Banach modules, we introduce a certain type of spectrum for the elements of $\mathcal{X}$ and we also introduce a certain subset of $\mathcal{X}$ which behaves as the set of invertible elements of a commutative unital Banach algebra. Among other things, we use these sets to give some Gleason–Kahane–Żelazko theorems for left Banach $A$ -modules.
</p>projecteuclid.org/euclid.bjma/1502935411_20171004220208Wed, 04 Oct 2017 22:02 EDTDuality properties for generalized frameshttps://projecteuclid.org/euclid.bjma/1503993619<strong>F. Enayati</strong>, <strong>M. S. Asgari</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 880--898.</p><p><strong>Abstract:</strong><br/>
We introduce the concept of Riesz-dual sequences for g-frames. In this paper we show that, for any sequence of operators, we can construct a corresponding sequence of operators with a kind of duality relation between them. This construction is used to prove duality principles in g-frame theory, which can be regarded as general versions of several well-known duality principles for frames. We also derive a simple characterization of a g-Riesz basic sequence as a g-R-dual sequence of a g-frame in the tight case.
</p>projecteuclid.org/euclid.bjma/1503993619_20171004220208Wed, 04 Oct 2017 22:02 EDTCharacterizations of asymmetric truncated Toeplitz operatorshttps://projecteuclid.org/euclid.bjma/1504080092<strong>Crisina Câmara</strong>, <strong>Joanna Jurasik</strong>, <strong>Kamila Kliś-Garlicka</strong>, <strong>Marek Ptak</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 899--922.</p><p><strong>Abstract:</strong><br/>
The aim of this paper is to investigate asymmetric truncated Toeplitz operators with $L^{2}$ -symbols between two different model spaces given by inner functions such that one divides the other. The class of symbols corresponding to the zero operator is described. Asymmetric truncated Toeplitz operators are characterized in terms of operators of rank at most $2$ , and the relations with the corresponding symbols are studied.
</p>projecteuclid.org/euclid.bjma/1504080092_20171004220208Wed, 04 Oct 2017 22:02 EDTNon-self-adjoint Schrödinger operators with nonlocal one-point interactionshttps://projecteuclid.org/euclid.bjma/1505116817<strong>Sergii Kuzhel</strong>, <strong>Miloslav Znojil</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 923--944.</p><p><strong>Abstract:</strong><br/>
We generalize and study, within the framework of quantum mechanics and working with $1$ -dimensional, manifestly non-Hermitian Hamiltonians $H=-{d^{2}}/{dx^{2}}+V$ , the traditional class of exactly solvable models with local point interactions $V=V(x)$ . We discuss the consequences of the use of nonlocal point interactions such that $(Vf)(x)=\int K(x,s)f(s)\,ds$ by means of the suitably adapted formalism of boundary triplets.
</p>projecteuclid.org/euclid.bjma/1505116817_20171004220208Wed, 04 Oct 2017 22:02 EDTLinear dependency of translations and square-integrable representationshttps://projecteuclid.org/euclid.bjma/1504836178<strong>Peter A. Linnell</strong>, <strong>Michael J. Puls</strong>, <strong>Ahmed Roman</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Volume 11, Number 4, 945--962.</p><p><strong>Abstract:</strong><br/>
Let $G$ be a locally compact group. We examine the problem of determining when nonzero functions in $L^{2}(G)$ have linearly independent left translations. In particular, we establish some results for the case when $G$ has an irreducible, square-integrable, unitary representation. We apply these results to the special cases of the affine group, the shearlet group, and the Weyl–Heisenberg group. We also investigate the case when $G$ has an abelian, closed subgroup of finite index.
</p>projecteuclid.org/euclid.bjma/1504836178_20171004220208Wed, 04 Oct 2017 22:02 EDTMultiplicative operator functions and abstract Cauchy problemshttps://projecteuclid.org/euclid.bjma/1515402092<strong>Felix Früchtl</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 27 pages.</p><p><strong>Abstract:</strong><br/>
We use the duality between functional and differential equations to solve several classes of abstract Cauchy problems related to special functions. As a general framework, we investigate operator functions which are multiplicative with respect to convolution of a hypergroup. This setting contains all representations of (hyper)groups, and properties of continuity are shown; examples are provided by translation operator functions on homogeneous Banach spaces and weakly stationary processes indexed by hypergroups. Then we show that the concept of a multiplicative operator function can be used to solve a variety of abstract Cauchy problems, containing discrete, compact, and noncompact problems, including $C_{0}$ -groups and cosine operator functions, and more generally, Sturm–Liouville operator functions.
</p>projecteuclid.org/euclid.bjma/1515402092_20180108040158Mon, 08 Jan 2018 04:01 ESTLower and upper local uniform $K$ -monotonicity in symmetric spaceshttps://projecteuclid.org/euclid.bjma/1513674116<strong>Maciej Ciesielski</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 17 pages.</p><p><strong>Abstract:</strong><br/>
Using the local approach to the global structure of a symmetric space $E$ , we establish a relationship between strict $K$ -monotonicity, lower (resp., upper) local uniform $K$ -monotonicity, order continuity, and the Kadec–Klee property for global convergence in measure. We also answer the question: Under which condition does upper local uniform $K$ -monotonicity coincide with upper local uniform monotonicity? Finally, we present a correlation between $K$ -order continuity and lower local uniform $K$ -monotonicity in a symmetric space $E$ under some additional assumptions on $E$ .
</p>projecteuclid.org/euclid.bjma/1513674116_20180108040158Mon, 08 Jan 2018 04:01 ESTRelatively compact sets in variable-exponent Lebesgue spaceshttps://projecteuclid.org/euclid.bjma/1513674117<strong>Rovshan Bandaliyev</strong>, <strong>Przemysław Górka</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 16 pages.</p><p><strong>Abstract:</strong><br/>
We study totally bounded sets in variable Lebesgue spaces. The full characterization of this kind of sets is given for the case of variable Lebesgue space on metric measure spaces. Furthermore, the sufficient conditions for compactness are shown without assuming $\log$ -Hölder continuity of the exponent.
</p>projecteuclid.org/euclid.bjma/1513674117_20180108040158Mon, 08 Jan 2018 04:01 ESTReducing subspaces for a class of nonanalytic Toeplitz operatorshttps://projecteuclid.org/euclid.bjma/1513674118<strong>Jia Deng</strong>, <strong>Yufeng Lu</strong>, <strong>Yanyue Shi</strong>, <strong>Yinyin Hu</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 25 pages.</p><p><strong>Abstract:</strong><br/>
In this paper, we give a uniform characterization for the reducing subspaces for $T_{\varphi}$ with the symbol $\varphi(z)=z^{k}+\bar{z}^{l}$ ( $k,l\in\mathbb{Z}_{+}^{2}$ ) on the Bergman spaces over the bidisk, including the known cases that $\varphi(z_{1},z_{2})=z_{1}^{N}z_{2}^{M}$ and $\varphi(z_{1},z_{2})=z_{1}^{N}+\overline{z}_{2}^{M}$ with $N,M\in\mathbb{Z}_{+}$ . Meanwhile, the reducing subspaces for $T_{z^{N}+\overline{z}^{M}}$ ( $N,M\in \mathbb{Z}_{+}$ ) on the Bergman space over the unit disk are also described. Finally, we state these results in terms of the commutant algebra $\mathcal{V}^{*}(\varphi)$ .
</p>projecteuclid.org/euclid.bjma/1513674118_20180108040158Mon, 08 Jan 2018 04:01 ESTWeighted Banach spaces of Lipschitz functionshttps://projecteuclid.org/euclid.bjma/1513674119<strong>A. Jiménez-Vargas</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 18 pages.</p><p><strong>Abstract:</strong><br/>
Given a pointed metric space $X$ and a weight $v$ on $\widetilde{X}$ (the complement of the diagonal set in $X\times X$ ), let $\mathrm{Lip}_{v}(X)$ and $\mathrm{lip}_{v}(X)$ denote the Banach spaces of all scalar-valued Lipschitz functions $f$ on $X$ vanishing at the basepoint such that $v\Phi(f)$ is bounded and $v\Phi(f)$ vanishes at infinity on $\widetilde{X}$ , respectively, where $\Phi(f)$ is the de Leeuw’s map of $f$ on $\widetilde{X}$ , under the weighted Lipschitz norm. The space $\mathrm{Lip}_{v}(X)$ has an isometric predual $\mathcal{F}_{v}(X)$ and it is proved that $(\mathrm{Lip}_{v}(X),\tau_{\operatorname{bw}^{*}})=(\mathcal{F}_{v}(X)^{*},\tau_{c})$ and $\mathcal{F}_{v}(X)=((\mathrm{Lip}_{v}(X),\tau_{\operatorname{bw}^{*}})',\tau_{c})$ , where $\tau_{\operatorname{bw}^{*}}$ denotes the bounded weak∗ topology and $\tau_{c}$ the topology of uniform convergence on compact sets. The linearization of the elements of $\mathrm{Lip}_{v}(X)$ is also tackled. Assuming that $X$ is compact, we address the question as to when $\mathrm{Lip}_{v}(X)$ is canonically isometrically isomorphic to $\mathrm{lip}_{v}(X)^{**}$ , and we show that this is the case whenever $\mathrm{lip}_{v}(X)$ is an M-ideal in $\mathrm{Lip}_{v}(X)$ and the so-called associated weights $\widetilde{v}_{L}$ and $\widetilde{v}_{l}$ coincide.
</p>projecteuclid.org/euclid.bjma/1513674119_20180108040158Mon, 08 Jan 2018 04:01 ESTGeneralized frames for operators associated with atomic systemshttps://projecteuclid.org/euclid.bjma/1512464418<strong>Dongwei Li</strong>, <strong>Jinsong Leng</strong>, <strong>Tingzhu Huang</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 16 pages.</p><p><strong>Abstract:</strong><br/>
In this paper, we investigate the g-frame and Bessel g-sequence related to a linear bounded operator $K$ in Hilbert space, which we call a $K$ -g-frame and a $K$ -dual Bessel g-sequence , respectively. Since the frame operator for a $K$ -g-frame may not be invertible, there is no classical canonical dual for a $K$ -g-frame. So we characterize the concept of a canonical $K$ -dual Bessel g-sequence of a $K$ -g-frame that generalizes the classical dual of a g-frame. Moreover, we use a family of linear operators to characterize atomic systems. We also consider the construction of new atomic systems from given ones and bounded operators.
</p>projecteuclid.org/euclid.bjma/1512464418_20180108040158Mon, 08 Jan 2018 04:01 ESTCalderón–Lozanovskii interpolation on quasi-Banach latticeshttps://projecteuclid.org/euclid.bjma/1512464419<strong>Yves Raynaud</strong>, <strong>Pedro Tradacete</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 20 pages.</p><p><strong>Abstract:</strong><br/>
We consider the Calderón–Lozanovskii construction $\varphi(X_{0},X_{1})$ in the context of quasi-Banach lattices, and we provide an extension of a result by Ovchinnikov concerning the associated interpolation methods $\varphi^{c}$ and $\varphi^{0}$ . Our approach is based on the interpolation properties of $(\infty,1)$ -regular operators between quasi-Banach lattices.
</p>projecteuclid.org/euclid.bjma/1512464419_20180108040158Mon, 08 Jan 2018 04:01 ESTStability of average roughness, octahedrality, and strong diameter $2$ properties of Banach spaces with respect to absolute sumshttps://projecteuclid.org/euclid.bjma/1512464420<strong>Rainis Haller</strong>, <strong>Johann Langemets</strong>, <strong>Rihhard Nadel</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 18 pages.</p><p><strong>Abstract:</strong><br/>
We prove that, if Banach spaces $X$ and $Y$ are $\delta$ -average rough, then their direct sum with respect to an absolute norm $N$ is $\delta/N(1,1)$ -average rough. In particular, for octahedral $X$ and $Y$ and for $p$ in $(1,\infty)$ , the space $X\oplus_{p}Y$ is $2^{1-1/p}$ -average rough, which is in general optimal. Another consequence is that for any $\delta$ in $(1,2]$ there is a Banach space which is exactly $\delta$ -average rough. We give a complete characterization when an absolute sum of two Banach spaces is octahedral or has the strong diameter 2 property. However, among all of the absolute sums, the diametral strong diameter 2 property is stable only for 1- and $\infty$ -sums.
</p>projecteuclid.org/euclid.bjma/1512464420_20180108040158Mon, 08 Jan 2018 04:01 ESTLocal matrix homotopies and soft torihttps://projecteuclid.org/euclid.bjma/1510909220<strong>Terry A. Loring</strong>, <strong>Fredy Vides</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 24 pages.</p><p><strong>Abstract:</strong><br/> We present solutions to local connectivity problems in matrix representations of the form $C([-1,1]^{N})\to C^{*}(u_{\varepsilon},v_{\varepsilon})$ , with $C_{\varepsilon}(\mathbb{T}^{2})\twoheadrightarrow C^{*}(u_{\varepsilon},v_{\varepsilon})$ for any $\varepsilon\in[0,2]$ and any integer $n\geq1$ , where $C^{*}(u_{\varepsilon},v_{\varepsilon})\subseteq M_{n}$ is an arbitrary matrix representation of the universal $C^{*}$ -algebra $C_{\varepsilon}(\mathbb{T}^{2})$ that denotes the soft torus . We solve the connectivity problems by introducing the so-called toroidal matrix links , which can be interpreted as normal contractive matrix analogies of free homotopies in differential algebraic topology. To deal with the locality constraints, we have combined some techniques introduced in this article with some techniques from matrix geometry, combinatorial optimization, and classification and representation theory of $C^{*}$ -algebras. </p>projecteuclid.org/euclid.bjma/1510909220_20180108040158Mon, 08 Jan 2018 04:01 ESTKolmogorov-type and general extension results for nonlinear expectationshttps://projecteuclid.org/euclid.bjma/1510909221<strong>Robert Denk</strong>, <strong>Michael Kupper</strong>, <strong>Max Nendel</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 26 pages.</p><p><strong>Abstract:</strong><br/>
We provide extension procedures for nonlinear expectations to the space of all bounded measurable functions. We first discuss a maximal extension for convex expectations which have a representation in terms of finitely additive measures. One of the main results of this article is an extension procedure for convex expectations which are continuous from above and therefore admit a representation in terms of countably additive measures. This can be seen as a nonlinear version of the Daniell–Stone theorem. From this, we deduce a robust Kolmogorov extension theorem which is then used to extend nonlinear kernels to an infinite-dimensional path space. We then apply this theorem to construct nonlinear Markov processes with a given family of nonlinear transition kernels.
</p>projecteuclid.org/euclid.bjma/1510909221_20180108040158Mon, 08 Jan 2018 04:01 ESTNew $L^{p}$ -inequalities for hyperbolic weights concerning the operators with complex Gaussian kernelshttps://projecteuclid.org/euclid.bjma/1510909222<strong>Benito J. González</strong>, <strong>Emilio R. Negrín</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 23 pages.</p><p><strong>Abstract:</strong><br/>
In this article the authors present a systematic study of several new $L^{p}$ -boundedness properties and Parseval-type relations concerning the operators with complex Gaussian kernels over the spaces $L^{p}(\mathbb{R},\cosh(\alpha x)\,dx)$ and $L^{p}(\mathbb{R},\cosh(\alpha x^{2})\,dx)$ , $1\leq p\leq\infty$ , $\alpha\in\mathbb{R}$ . Relevant connections with various earlier related results are also pointed out.
</p>projecteuclid.org/euclid.bjma/1510909222_20180108040158Mon, 08 Jan 2018 04:01 ESTNorm convergence of logarithmic means on unbounded Vilenkin groupshttps://projecteuclid.org/euclid.bjma/1510909224<strong>György Gát</strong>, <strong>Ushangi Goginava</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 17 pages.</p><p><strong>Abstract:</strong><br/>
In this paper we prove that, in the case of some unbounded Vilenkin groups, the Riesz logarithmic means converges in the norm of the spaces $X(G)$ for every $f\in X(G)$ , where by $X(G)$ we denote either the class of continuous functions with supremum norm or the class of integrable functions.
</p>projecteuclid.org/euclid.bjma/1510909224_20180108040158Mon, 08 Jan 2018 04:01 ESTCohomology for small categories: $k$ -graphs and groupoidshttps://projecteuclid.org/euclid.bjma/1510283128<strong>Elizabeth Gillaspy</strong>, <strong>Alexander Kumjian</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 28 pages.</p><p><strong>Abstract:</strong><br/>
Given a higher-rank graph $\Lambda$ , we investigate the relationship between the cohomology of $\Lambda$ and the cohomology of the associated groupoid $\mathcal{G}_{\Lambda}$ . We define an exact functor between the Abelian category of right modules over a higher-rank graph $\Lambda$ and the category of $\mathcal{G}_{\Lambda}$ -sheaves, where $\mathcal{G}_{\Lambda}$ is the path groupoid of $\Lambda$ . We use this functor to construct compatible homomorphisms from both the cohomology of $\Lambda$ with coefficients in a right $\Lambda$ -module, and the continuous cocycle cohomology of $\mathcal{G}_{\Lambda}$ with values in the corresponding $\mathcal{G}_{\Lambda}$ -sheaf, into the sheaf cohomology of $\mathcal{G}_{\Lambda}$ .
</p>projecteuclid.org/euclid.bjma/1510283128_20180108040158Mon, 08 Jan 2018 04:01 ESTVector lattices and $f$ -algebras: The classical inequalitieshttps://projecteuclid.org/euclid.bjma/1510283129<strong>G. Buskes</strong>, <strong>C. Schwanke</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 15 pages.</p><p><strong>Abstract:</strong><br/>
We present some of the classical inequalities in analysis in the context of Archimedean (real or complex) vector lattices and $f$ -algebras. In particular, we prove an identity for sesquilinear maps from the Cartesian square of a vector space to a geometric mean closed Archimedean vector lattice, from which a Cauchy–Schwarz inequality follows. A reformulation of this result for sesquilinear maps with a geometric mean closed semiprime Archimedean $f$ -algebra as codomain is also given. In addition, a sufficient and necessary condition for equality is presented. We also prove a Hölder inequality for weighted geometric mean closed Archimedean $\Phi$ -algebras, substantially improving results by K. Boulabiar and M. A. Toumi. As a consequence, a Minkowski inequality for weighted geometric mean closed Archimedean $\Phi$ -algebras is obtained.
</p>projecteuclid.org/euclid.bjma/1510283129_20180108040158Mon, 08 Jan 2018 04:01 ESTA variant of the Hankel multiplierhttps://projecteuclid.org/euclid.bjma/1510110961<strong>Saifallah Ghobber</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 23 pages.</p><p><strong>Abstract:</strong><br/>
The first aim of this article is to survey and revisit some uncertainty principles for the Hankel transform by means of the Hankel multiplier. Then we define the wavelet Hankel multiplier and study its boundedness and Schatten-class properties. Finally, we prove that the wavelet Hankel multiplier is unitary equivalent to a scalar multiple of the phase space restriction operator, for which we deduce a trace formula.
</p>projecteuclid.org/euclid.bjma/1510110961_20180108040158Mon, 08 Jan 2018 04:01 ESTToeplitz operators on weighted harmonic Bergman spaceshttps://projecteuclid.org/euclid.bjma/1510110962<strong>Zipeng Wang</strong>, <strong>Xianfeng Zhao</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 35 pages.</p><p><strong>Abstract:</strong><br/>
In this article, we study Toeplitz operators with nonnegative symbols on the $\mathcal{A}_{2}$ -weighted harmonic Bergman space. We characterize the boundedness, compactness, and invertibility of Toeplitz operators with nonnegative symbols on this space.
</p>projecteuclid.org/euclid.bjma/1510110962_20180108040158Mon, 08 Jan 2018 04:01 ESTOn the universal function for weighted spaces $L^{p}_{\mu}[0,1]$ , $p\geq 1$https://projecteuclid.org/euclid.bjma/1507017624<strong>Martin Grigoryan</strong>, <strong>Tigran Grigoryan</strong>, <strong>Artsrun Sargsyan</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 22 pages.</p><p><strong>Abstract:</strong><br/>
In this article, we show that there exist a function $g\in L^{1}[0,1]$ and a weight function $0\lt \mu(x)\leq1$ so that $g$ is universal for each class $L^{p}_{\mu}[0,1]$ , $p\geq 1$ , with respect to signs-subseries of its Fourier–Walsh series.
</p>projecteuclid.org/euclid.bjma/1507017624_20180108040158Mon, 08 Jan 2018 04:01 ESTHörmander-type theorems on unimodular multipliers and applications to modulation spaceshttps://projecteuclid.org/euclid.bjma/1507017625<strong>Qiang Huang</strong>, <strong>Jiecheng Chen</strong>, <strong>Dashan Fan</strong>, <strong>Xiangrong Zhu</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 19 pages.</p><p><strong>Abstract:</strong><br/>
In this article, for the unimodular multipliers $e^{i\mu (D)}$ , we establish two Hörmander-type multiplier theorems by assuming conditions on their phase functions $\mu $ . As applications, we obtain two multiplier theorems particularly fitting for the modulation spaces, thus allowing us to extend and improve some known results.
</p>projecteuclid.org/euclid.bjma/1507017625_20180108040158Mon, 08 Jan 2018 04:01 ESTApproximate uniqueness for maps from $C(X)$ into simple real rank $0$ C∗-algebrashttps://projecteuclid.org/euclid.bjma/1506412929<strong>P. W. Ng</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 18 pages.</p><p><strong>Abstract:</strong><br/>
Let $X$ be a finite CW-complex, and let $\mathcal{A}$ be a unital separable simple finite $\mathcal{Z}$ -stable C∗-algebra with real rank $0$ . We prove an approximate uniqueness theorem for almost multiplicative contractive completely positive linear maps from $C(X)$ into $\mathcal{A}$ . We also give conditions for when such a map can, within a certain “error,” be approximated by a finite-dimensional ∗-homomorphism.
</p>projecteuclid.org/euclid.bjma/1506412929_20180108040158Mon, 08 Jan 2018 04:01 ESTDaugavet property and separability in Banach spaceshttps://projecteuclid.org/euclid.bjma/1505980813<strong>Abraham Rueda Zoca</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 17 pages.</p><p><strong>Abstract:</strong><br/>
We give a characterization of the separable Banach spaces with the Daugavet property which is applied to study the Daugavet property in the projective tensor product of an $L$ -embedded space with another nonzero Banach space. The former characterization also motivates the introduction and short study of two indices related to the Daugavet property.
</p>projecteuclid.org/euclid.bjma/1505980813_20180108040158Mon, 08 Jan 2018 04:01 ESTNearly relatively compact projections in operator algebrashttps://projecteuclid.org/euclid.bjma/1505959314<strong>Lawrence G. Brown</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 35 pages.</p><p><strong>Abstract:</strong><br/>
Let $A$ be a $C^{*}$ -algebra, and let $A^{**}$ be its enveloping von Neumann algebra. Akemann suggested a kind of noncommutative topology in which certain projections in $A^{**}$ play the role of open sets, and he used two operator inequalities in connection with compactness. Both of these inequalities are equivalent to compactness for a closed projection in $A^{**}$ , but only one is equivalent to relative compactness for a general projection. A third operator inequality, also related to compactness, was used by the author. The study of all three inequalities can be unified by considering a numerical invariant which is equivalent to the distance of a projection from the set of relatively compact projections. Tomita’s concept of regularity of projections seems relevant, and so we give some results and examples on regularity. We also include a few related results on semicontinuity.
</p>projecteuclid.org/euclid.bjma/1505959314_20180108040158Mon, 08 Jan 2018 04:01 ESTOn Banach spaces of vector-valued random variables and their duals motivated by risk measureshttps://projecteuclid.org/euclid.bjma/1504857611<strong>Thomas Kalmes</strong>, <strong>Alois Pichler</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 35 pages.</p><p><strong>Abstract:</strong><br/>
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. Since the risk functionals cannot be defined on strictly larger spaces of random variables, this creates an area of particular interest with regard to 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.
</p>projecteuclid.org/euclid.bjma/1504857611_20180108040158Mon, 08 Jan 2018 04:01 ESTA generalized Hilbert operator acting on conformally invariant spaceshttps://projecteuclid.org/euclid.bjma/1504857614<strong>Daniel Girela</strong>, <strong>Noel Merchán</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 25 pages.</p><p><strong>Abstract:</strong><br/>
If $\mu$ is a positive Borel measure on the interval $[0,1)$ , we let $\mathcal{H}_{\mu}$ be the Hankel matrix $\mathcal{H}_{\mu}=(\mu_{n,k})_{n,k\ge0}$ with entries $\mu_{n,k}=\mu_{n+k}$ , where, for $n=0,1,2,\dots$ , $\mu_{n}$ denotes the moment of order $n$ of $\mu$ . This matrix formally induces the operator \[\mathcal{H}_{\mu}(f)(z)=\sum_{n=0}^{\infty}(\sum_{k=0}^{\infty}\mu_{n,k}{a_{k}})z^{n}\] on the space of all analytic functions $f(z)=\sum_{k=0}^{\infty}a_{k}z^{k}$ , in the unit disk $\mathbb{D}$ . This is a natural generalization of the classical Hilbert operator. The action of the operators $H_{\mu}$ on Hardy spaces has been recently studied. This article is devoted to a study of the operators $H_{\mu}$ acting on certain conformally invariant spaces of analytic functions on the disk such as the Bloch space, the space BMOA, the analytic Besov spaces, and the $Q_{s}$ -spaces.
</p>projecteuclid.org/euclid.bjma/1504857614_20180108040158Mon, 08 Jan 2018 04:01 ESTToeplitz operators on the space of real analytic functions: The Fredholm propertyhttps://projecteuclid.org/euclid.bjma/1501812082<strong>Pawel Domański</strong>, <strong>Michal Jasiczak</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 37 pages.</p><p><strong>Abstract:</strong><br/>
We completely characterize those continuous operators on the space of real analytic functions on the real line for which the associated matrix is Toeplitz (that is, we describe Toeplitz operators on this space). We also prove a necessary and sufficient condition for such operators to be Fredholm operators. While the space of real analytic functions is neither Banach space nor has a basis which makes available methods completely different from classical cases of Hardy spaces or Bergman spaces, nevertheless the results themselves show surprisingly strong similarity to the classical Hardy-space theory.
</p>projecteuclid.org/euclid.bjma/1501812082_20180108040158Mon, 08 Jan 2018 04:01 ESTNew function spaces related to Morrey spaces and the Fourier transformhttps://projecteuclid.org/euclid.bjma/1497600064<strong>Shohei Nakamura</strong>, <strong>Yoshihiro Sawano</strong>. <p><strong>Source: </strong>Banach Journal of Mathematical Analysis, Advance publication, 30 pages.</p><p><strong>Abstract:</strong><br/>
We introduce new function spaces to handle the Fourier transform on Morrey spaces and investigate fundamental properties of the spaces. As an application, we generalize the Stein–Tomas Strichartz estimate to our spaces. The geometric property of Morrey spaces and related function spaces will improve some well-known estimates.
</p>projecteuclid.org/euclid.bjma/1497600064_20180108040158Mon, 08 Jan 2018 04:01 EST