The Šilov Boundary for Operator Spaces

Motivated by the recent interest in the examination of unital completely positive maps and their effects in C*-theory, we revisit an older result concerning the existence of the ?ilov ideal. The direct proof of Hamana’s Theorem for the existence of an injective envelope for a unital operator subspace X of some ${\mathcal{B}(H)}$ that we provide implies that the ?ilov ideal is the intersection of C*(X) with any maximal boundary operator subsystem in ${\mathcal{B}(H)}$ . As an immediate consequence we deduce that the ?ilov ideal is the biggest boundary operator subsystem for X in C*(X). The new proof of the existence of the ?ilov ideal that we give does not use the existence of maximal dilations, provided by Drits- chel and McCullough, and so it is independent of the one given by Arveson. As a consequence, the ?ilov ideal can be seen as the set that contains the abnormalities in a C*-cover ${(C, \iota)}$ of X for all the extensions of the identity map ${{\rm id}_{\iota(X)}}$ . The interpretation of our results in terms of ucp maps characterizes the maximal boundary subsystems of X in ${\mathcal{B}(H)}$ as kernels of X-projections that induce completely minimal X-seminorms; equivalently, X-minimal projections with range being an injective envelope, that we view from now on as the ?ilov boundary for X.     

Hankel Operators on Holomorphic Hardy–Orlicz Spaces

We characterize the symbols of Hankel operators that extend into bounded operators from the Hardy–Orlicz ${\mathcal H^{\Phi_1}(\mathbb B^n)}$ into ${\mathcal H^{\Phi_2}(\mathbb B^n)}$ in the unit ball of ${\mathbb C^n}$ , in the case where the growth functions ${\Phi_1}$ and ${\Phi_2}$ are either concave or convex. The case where the growth functions are both concave has been studied by Bonami and Sehba. We also obtain several weak factorization theorems for functions in ${\mathcal H^{\Phi}(\mathbb B^n)}$ , with concave growth function, in terms of products of Hardy–Orlicz functions with convex growth functions.     

Strongly Singular Calderon-Zygmund Operator and Commutator on Morrey Type Spaces

In this paper, the author considers the boundedness of strongly singular Calderdn Zygmund operator and commutator generated by this operator and Lipschitz function on the classical Morrey space and generalized Morrey space. Moreover, the boundedness of strongly singular Calderón- Zygmund operator on the predual of Morrey space is discussed.     

Multilinear Calderón-Zygmund Operator on Products of Hardy Spaces

In this paper, the authors establish the boundedness of the multilinear Calderón-Zygmund operator from products of Hardy spaces into Hardy spaces.     

The Distance to Upper Triangular Operator Spaces of Von Neumann Algebras

Ｔｈｒｏｕｇｈｏｕｔｔｈｉｓｐａｐｅｒ，ｔｈｅｎｏｎｚｅｒｏＨｉｌｂｅｒｔｓｐａｃｅＨｕｎｄｅｒｃｏｎｓｉｄｅｒａｔｉｏｎｉｓｃｏｍｌｅｘａｎｄｓｅｐａｒａｂｌｅ．ＬｅｔＢ（Ｈ）ｂｅｔｈｅｓｅｔｏｆａｌｌｉｎｅａｒｂｏｕｎｄｅｄｏｐｅｒａｔｏｒｓｏｎ...     

The Degree Theory of a New Operator

§１．　ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｔｈｅｄｅｇｒｅｅｔｈｅｏｒｙｆｏｒａｋ－ｓｅｔ－ｃｏｎｔｒａｃｔｏｐｅｒａｔｏｒｈａｓｍａｎｙａｐｐｌｉｃａｔｉｏｎｓｏｎｔｈｅｅｘｉｓｔｅｎｃｅｏｆｔｈｅｓｏｌｕｔｉｏｎｓｏｆｓｏｍｅｅｑｕａｔｉｏｎｓ（ｓｅｅ［１］，［２］，［３］）．Ｈｏｗｅｖｅｒ，ｓｏｍｅｏｐｅｒａ－ｔｏｒｓａｒｅｎｏｔｋ－ｓｅｔ－ｃｏｎｔｒａｃｔｏｐｅｒａｔｏｒｓ．Ｉｔｉｓａｎｅｗｐｒｏｂｌｅｍｔｈａｔｗｅｅｓｔａｂｌｉｓｈａｄｅｇｒｅｅｔｈｅｏｒｙｆｏ…     

The Boundedness of the Commutator for Riesz Potential Associated with Schr dinger Operator on Morrey Spaces

Let L =-△ + V be the Schr dinger operator on Rd, where △ is the Laplacian on Rdand V≠0 is a nonnegative function satisfying the reverse H lder's inequality.The authors prove that Riesz potential Iβand its commutator [b, Iβ] associated with L map from Mp,qα,vinto Mp1,q1α,v.     

The Boundedness of the Commutator for Riesz Potential Associated with Schr ¨odinger Operator on Morrey Spaces

Let L=??+V be the Schr ¨odinger operator on Rd, where?is the Laplacian on Rd and V 6=0 is a nonnegative function satisfying the reverse H¨older’s inequality. The authors prove that Riesz potential Iβa...     

The Cesàro Operator in Growth Banach Spaces of Analytic Functions

The Cesàro operator C, when acting in the classical growth Banach spaces \({A^{-\gamma}}\) and \({A_0^{-\gamma}}\), for \({\gamma} > 0\), of analytic functions on \({\mathbb{D}}\), is investigated. Based on a detailed knowledge of their spectra (due to A. Aleman and A.-M. Persson) we are able to determine the norms of these operators precisely. It is then possible to characterize the mean ergodic and related properties of C acting in these spaces. In addition, we determine the largest Banach space of analytic functions on \({\mathbb{D}}\) which C maps into \({A^{-\gamma}}\) (resp. into \({A_0^{-\gamma}}\)); this optimal domain space always contains \({A^{-\gamma}}\) (resp. \({A_0^{-\gamma}}\)) as a proper subspace.     

Weak-Type Boundedness of the Hardy–Littlewood Maximal Operator on Weighted Lorentz Spaces

The main goal of this paper is to provide a characterization of the weak-type boundedness of the Hardy–Littlewood maximal operator, M, on weighted Lorentz spaces \(\Lambda ^p_u(w)\), whenever \(p>1\). This solves a problem left open in (Carro et al., Mem Am Math Soc. 2007). Moreover, with this result, we complete the program of unifying the study of the boundedness of M on weighted Lebesgue spaces and classical Lorentz spaces, which was initiated in the aforementioned monograph.     

The Fractional Maximal Operator and Marcinkiewicz Integrals Associated with Schr?dinger Operators on Morrey Spaces with Variable Exponent

In this paper, we prove the boundedness of the fractional maximal operator, Hardy-Littlewood maximal operator and marcinkiewicz integrals associated with Schr ?dinger operator on Morrey spaces with variable exponent.     

The Dyadic Cesàro Operator on R+

The dyadic Cesàro operator C is introduced for functions in the space L ¹ := L ¹(R ₊) by means of the Walsh-Fourier transform defined by

The Trace of Nuclear Operators on L p (μ) for σ-Finite Borel Measures on Second Countable Spaces

Let Ω be a second countable topological space and μ be a σ−finite measure on the Borel sets M{\mathcal{M}}. Let T be a nuclear operator on L^p(W,M,m){L^p({\Omega},{\mathcal{M}},\mu) }, 1 < p < ∞, in this work we establish a formula for the trace of T. A preliminary trace formula is established applying the general theory of traces on operator ideals introduced by Pietsch and a characterization of nuclear operators for σ−finite measures. We also use the Doob’s maximal theorem for martingales with the purpose of studying the kernel k(x, y) of T on the diagonal.     

Besov and Hardy Spaces Associated with the Schrödinger Operator on the Heisenberg Group

We introduce the Besov space $\dot{B}^{0,L}_{1,1}$ associated with the Schrödinger operator L with a nonnegative potential satisfying a reverse Hölder inequality on the Heisenberg group, and obtain the molecular decomposition. We also develop the Hardy space $H_{L}^{1}$ associated with the Schrödinger operator via the Littlewood–Paley area function and give equivalent characterizations via atoms, molecules, and the maximal function. Moreover, using the molecular decomposition, we prove that $\dot{B}^{0,L}_{1,1}$ is a subspace of $H_{L}^{1}$ .     

Inverse Problems for the Dirac Operator on a Star Graph

Following the previous work, we shall study some inverse problems for the Dirac operator on an equilateral star graph. It is proven that the so-called Weyl function uniquely determines the potentials. Furthermore, we pay attention to the inverse problem of recovering the potentials from the spectral data, which consists of the eigenvalues and weight matrices, and present a constructive algorithm. The basic tool in this paper is the method of spectral mappings developed by Yurko.     

The Schrödinger Equation Type with a Nonelliptic Operator

We consider some linear Schrödinger equation with variable coefficients associated to a smooth symmetric metric g which can be degenerate, without sign and such that g has a submatrix of fixed rank v which is uniformly nondegenerate. In this general setting we prove Strichartz estimates with a loss of derivative on the solution. We also discuss the problem of the control of high frequencies. In particular, we prove that if the equation preserves the H ^s norm for all s ≥ 0, then we obtain almost the same Strichartz estimates as those for the Schrödinger equation associated to a Riemannian metric of dimension 2d ? v.     

Insertion of Continuous Real Functions on Spaces,Bispaces, Ordered Spaces and Pointfree Spaces—A Common Root

We characterize normal and extremally disconnected biframes in terms of the insertion of a continuous real function in between given lower and upper semicontinuous real functions and show this to be the common root of several classical and new insertion results concerning topological spaces, bitopological spaces, ordered topological spaces and locales.