Two-Wavelet Localization Operators on $$ L^p(\mathbb{R}^n) $$ for the Weyl-Heisenberg Group

We give results on the boundedness and compactness of localization operators with two admissible wavelets on for the Weyl-Heisenberg group.     

Multiplication Operators Defined by a Class of Polynomials on {L_a^2(\mathbb{D}^2)}

In this paper, we consider those multiplication operators M _p on \({L_a^2(\mathbb{D}^2)}\) defined by a class of polynomials p. Also, this paper consider the reducing subspaces of M _p , the von Neumann algebra \({ \mathcal{W}^*(p)}\) generated by M _p , and its commutant \({\mathcal{V}^*(p) = \mathcal{W}^*(p)'.}\) The structure of \({\mathcal{V}^*(p)}\) is completely determined, along with those reducing subspaces of M _p .     

The Essential Norm of Operators on {A^p_\alpha(\mathbb{B}_n)}

In this paper we characterize the compact operators on the weighted Bergman spaces ${A^p_\alpha(\mathbb{B}_n)}$ when 1 < p < ∞ and α > ?1. The main result shows that an operator on ${A^p_\alpha(\mathbb{B}_n)}$ is compact if and only if it belongs to the Toeplitz algebra and its Berezin transform vanishes on the boundary of the ball.     

Spectral Approximation and Index for Convolution Type Operators on Cones on L^{p}(\mathbb {R}^2)

We consider an algebra of operator sequences containing, among others, the approximation sequences to convolution type operators on cones acting on L^p(\mathbb R²)L^{p}(\mathbb {R}^2), with 1 < p < ∞. To each operator sequence (A_n) we associate a family of operators W_x(A_n) ? L(L^p(\mathbb R²))W_{x}(A_{n}) \in \mathcal {L}(L^{p}(\mathbb {R}^2)) parametrized by x in some index set. When all W_x(A_n) are Fredholm, the so-called approximation numbers of A_n have the α-splitting property with α being the sum of the kernel dimensions of W_x(A_n). Moreover, the sum of the indices of W_x(A_n) is zero. We also show that the index of some composed convolution-like operators is zero. Results on the convergence of the e\epsilon-pseudospectrum, norms of inverses and condition numbers are also obtained.     

On a Property of Continuous Operators in $$L^p (\mathbb{R}) $$ -Space

Mathematical Notes -     

The Fredholm Index of Locally Compact Band-dominated Operators on L^p \,(\user2{\mathbb{R}})

We establish a necessary and sufficient criterion for the Fredholmness of a general locally compact band-dominated operator A on and solve the long-standing problem of computing its Fredholm index in terms of the limit operators of A. The results are applied to operators of convolution type with almost periodic symbol.     

Commuting Toeplitz Operators with Harmonic Symbols on $A^2 (\overline{\mathbb{D}}, d\mu)$

For any given symmetric measure $µ$ on the closed unit disk $\overline{\mathbb{D}}$, we apply the Berezin transform to characterizing semi-commuting and commuting Toeplitz operators with bounded harmonic symbols on $A^2 (\overline{\mathbb{D}}, d\mu)$.     

On an Open Question about the Stability of the Finite Section Method for a Class of Convolution Type Operators

We clear up an open question on the characterization of the stability of operator sequences arising from the finite section method for convolution type operators with piecewise continuous and slowly oscillating generating functions. In particular, it turns out that the answer is different from what was conjectured so far and simplifies the previously known results.     

Multiplicity of solutions for a NLS equations with magnetic fields in mathbb {R}^{N}

We investigate the multiplicity of nontrivial weak solutions for a class of complex equations. This class of problems are related with the existence of solitary waves for a nonlinear Schödinger equation. The main result is established by using minimax methods and Lusternik–Schnirelman theory of critical points.     

Reachable sets for contact sub-Lorentzian structures on {\mathbb{R}^3} . Application to control affine systems on {\mathbb{R}^3} with a scalar input

In this paper, we investigate the structure of reachable sets for general contact sub-Lorentzian metrics on $ {\mathbb{R}^3} $ . In some particular cases, the presented method leads to explicit formulas for functions describing reachable sets. We also compute the image under exponential mapping and prove that the sub-Lorentzian distance is continuous for the mentioned structures. All presented results concerning reachable sets can be directly applied to generic control affine systems in $ {\mathbb{R}^3} $ with a scalar input u and constraints |u|??????.     

Uniform Boundedness and Decay Estimates for a System of Reaction-Diffusion Equations with a Triangular Diffusion Matrix on {\mathbb{R}^{n}}

This paper concerns with a class of reaction-diffusion systems with triangular diffusion matrix on the unbounded domain ${\mathbb{R}^{n}}$ . The system with diagonal diffusion matrix has been studied by J. D. Avrin and F. Rothe in [4]. We prove two new results about uniform boundedness to solutions of such class of reaction-diffusion systems in ${BUC(\mathbb{R}^{n})}$ , the space of bounded uniformly continuous functions from ${\mathbb{R}^{n}}$ to ${\mathbb{R}}$ .