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Consider the planar linear switched system $\dot x(t)=u(t)Ax(t)+(1-u(t))Bx(t),$ where $A$ and $B$ are two $2\times2$ real matrices, $x \in \R^2$, and $u(.):[0,\infty[\to\{0,1\}$ is a measurable function. In this paper we consider the…

Optimization and Control · Mathematics 2007-05-23 Moussa Balde , Ugo Boscain

We show that every matrix $A \in \mathbb{R}^{n\times n}$ is at least $\delta$$\|A\|$-close to a real matrix $A+E \in \mathbb{R}^{n\times n}$ whose eigenvectors have condition number at most $\tilde{O}_{n}(\delta^{-1})$. In fact, we prove…

Functional Analysis · Mathematics 2020-05-20 Vishesh Jain , Ashwin Sah , Mehtaab Sawhney

Our main interest in this paper is chiefly concerned with the conditions characterizing \textit{orthogonal and symplectic abstract differential geometries}. A detailed account about the sheaf-theoretic version of the \textit{symplectic…

Symplectic Geometry · Mathematics 2008-10-21 PP Ntumba , Ac Orioha

In this paper Witten type deformation of osp(1/2) algbera is introduced and its realization and matrix representation are obtained. The matrix representation is shown to be possible only when the dimension is odd.

q-alg · Mathematics 2008-02-03 W-S. Chung

In this short paper we show that March's criterion for the existence of a bounded non constant harmonic function on a weak model is also a necessary and sufficient condition for the solvability of the Dirichlet problem at infinity on a…

Differential Geometry · Mathematics 2023-05-30 Jhon E. Bravo , Jean C. Cortissoz

Let $\mathcal{A}=(A_{1},...,A_{n},...)$ be a finite or infinite sequence of $2\times2$ matrices with entries in an integral domain. We show that, except for a very special case, $\mathcal{A}$ is (simultaneously) triangularizable if and only…

Rings and Algebras · Mathematics 2021-10-19 Carlos A. A. Florentino

We proved that for any matrix dilation and for any positive integer $n$, there exists a compactly supported tight wavelet frame with approximation order $n$. Explicit methods for construction of dual and tight wavelet frames with a given…

Classical Analysis and ODEs · Mathematics 2007-05-23 M. Skopina

We prove bilinear inequalities for differential operators in $\mathbb{R}^2$. Such type inequalities turned out to be useful for anisotropic embedding theorems for overdetermined systems and the limiting order summation exponent. However,…

Classical Analysis and ODEs · Mathematics 2016-04-07 Dmitriy M. Stolyarov

In this paper we present parallel theories on constructing Wiener algebras in the bicomplex setting. With the appropriate symmetry condition, the bicomplex matrix valued case can be seen as a complex valued case and, in this matrix valued…

Complex Variables · Mathematics 2022-06-28 Daniel Alpay , Izchak Lewkowicz , Mihaela Vajiac

On a complex symplectic manifold we prove a finiteness result for the global sections of solutions of holonomic DQ-modules in two cases: (a) by assuming that there exists a Poisson compactification (b) in the algebraic case. This extends…

Algebraic Geometry · Mathematics 2021-05-19 Masaki Kashiwara , Pierre Schapira

Given $2n \times 2n$ real symmetric positive semidefinite matrix $A$ with symplectic kernel, there exists a real $2n \times 2n$ \emph{symplectic matrix} $M$ such that $M^TAM= D \oplus D$, where $D$ is an $n \times n$ non-negative diagonal…

Functional Analysis · Mathematics 2026-01-22 Temjensangba , Hemant K. Mishra , Niloy Paul

We propose a modeling framework for time-varying covariance matrices based on the assumption that the logarithm of a realized covariance matrix follows a matrix-variate oNrmal distribution. By operating in the space of symmetric matrices,…

Methodology · Statistics 2026-01-30 Edoardo Otranto

We discuss factorization of the hypergeometric-type difference equations on the uniform lattices and show how one can construct a dynamical algebra, which corresponds to each of these equations. Some examples are exhibited, in particular,…

Classical Analysis and ODEs · Mathematics 2010-03-26 R. Álvarez-Nodarse , N. M. Atakishiyev , R. S. Costas-Santos

A manifestly Lorentz-covariant calculus based on two matrix-coordinates and their associated derivatives is introduced. It allows formulating relativistic field theories in any even-dimensional spacetime. The construction extends a…

High Energy Physics - Theory · Physics 2007-05-23 L. P. Colatto , M. A. De Andrade , F. Toppan

In this paper we establish new renormalized oscillation theorems for discrete symplectic eigenvalue problems with Dirichlet boundary conditions. These theorems present the number of finite eigenvalues of the problem in arbitrary interval…

Dynamical Systems · Mathematics 2021-07-06 Julia Elyseeva

We give a natural definition of a Poisson Differential Algebra. Consistence conditions are formulated in geometrical terms. It is found that one can often locally put the Poisson structure on differential calculus in a simple canonical form…

q-alg · Mathematics 2009-10-30 Chong-Sun Chu , Pei-Ming Ho

This article studies canonical forms derived from the finest simultaneous block diagonalization of a set of symmetric matrices via congruence. Our technique relies on Harrison's center theory, which is extended from a single higher degree…

Rings and Algebras · Mathematics 2025-12-22 Lishan Fang , Hua-Lin Huang , Jiayan Huang

A positive definiteness criterion and, under the additional conditions, a nonnegativity criterion for a self-adjoint continuous operator matrix, acting in product of an arbitrary number of real separable Hilbert spaces, are obtained. As…

Functional Analysis · Mathematics 2010-09-02 I. V. Orlov , E. V. Bozhonok

Fillmore Theorem says that if A is an nxn complex non-scalar matrix and {\gamma}_1,...,{\gamma}_{n} are complex numbers with {\gamma}_1+...+{\gamma}_{n}=trA, then there exists a matrix B similar to A with diagonal entries…

Spectral Theory · Mathematics 2018-04-17 Ana I. Julio , Ricardo L. Soto

We show that almost commuting real orthogonal matrices are uniformly close to exactly commuting real orthogonal matrices. We prove the same for symplectic unitary matrices. This is in contrast to the general complex case, where not all…

Operator Algebras · Mathematics 2015-04-16 Terry A. Loring , Adam P. W. Sørensen