On the properties of a new tensor product of matrices

Previously, the author introduced a new tensor product of matrices according to which the matrix of the discrete Walsh-Paley transform can be represented as a power of the second-order discrete Walsh transform matrix H with respect to this product. This power is an analogue of the representation of the Sylvester-Hadamard matrix in the form of a Kronecker power of H. The properties of the new tensor product of matrices are examined and compared with those of the Kronecker product. An algebraic structure with the matrix H used as a generator element and with these two tensor products of matrices is constructed and analyzed. It is shown that the new tensor product operation proposed can be treated as a convenient mathematical language for describing the foundations of discrete Fourier analysis.     

Computational matrix representation modules for linear operators with explicit constructions for a class of lie operators

A linear mapping from a finite-dimensional linear space to another has a matrix representation. Certain multilinear functions are also matrix-representable. Using these representations, symbolic computations can be done numerically and hence more efficiently. This paper presents an organized procedure for constructing matrix representations for a class of linear operators on finite-dimensional spaces. First we present serial number functions for locating basis monomials in the linear space of homogeneous polynomials of fixed degree, ordered under structured lexicographies. Next basic lemmas describing the modular structure of matrix representations for operators constructed canonically from elementary operators are presented. Using these results, explicit matrix representations are then given for the Lie derivative and Lie-Poisson bracket operators defined on spaces of homogeneous polynomials. In particular, they are comprised of blocks obtained as Kronecker sums of modular components, each corresponding to specific Jordan blocks. At an implementation level, recursive programming is applied to construct these modular components explicitly. The results are also applied to computing power series approximations for the center manifold of a dynamical system. In this setting, the linear operator of interest is parameterized by two matrices, a generalization of the Lie-Poission bracket.     

广义酉矩阵与广义Hermite矩阵的张量积与诱导矩阵

本文研究了有限个广义酉矩阵与广义(反)Hermite矩阵的张量积和诱导矩阵.利用矩阵的张量积和诱导矩阵的性质,得到了它的张量积和诱导矩阵仍为广义酉矩阵与广义(反)Hermite矩阵.     

直积的推广与正交函数系的生成

Two new kinds of direct product of matrices are defined. Their properties are investigated . Direct products of matrix and set of continuous functions are also defined. Many complete sets of orthogonal functions, such as those sets given by Walsh [2], Paley [3], Chrestenson[4 ], and Watari [ 5 ], may be generated by : these newkinds of direct product . Direct products are also applicable to the generation of sets of piecewise orthogonal functions .     

Weighted Moore-Penrose inverses and fundamental theorem of even-order tensors with Einstein product

We treat even-order tensors with Einstein product as linear operators from tensor space to tensor space, define the null spaces and the ranges of tensors, and study their relationship. We extend the fundamental theorem of linear algebra for matrix spaces to tensor spaces. Using the new relationship, we characterize the least-squares (?) solutions to a multilinear system and establish the relationship between the minimum-norm (N) least-squares (?) solution of a multilinear system and the weighted Moore-Penrose inverse of its coefficient tensor. We also investigate a class of even-order tensors induced by matrices and obtain some interesting properties.     

Permanents and determinants with generic noncommuting entries

This paper studies some basic combinatorial properties of matrix functions of generic matrices. A generic matrix is one with entries from a free associative algebra, over a field, and on a finite set of non-commuting variables (i.e. a tensor algebra). The principal tools are shuffle products. Generic column and row permanents are defined and analogs of the Laplace and Cauchy-Binet theorems are derived in terms of shuffles. In this setting, the generic permanents include as special cases all of the classical matrix functions: Schur matrix functions, determinants, and permanents. 1980 Mathematics Classification 05, 15. Keywords: Shuffle product, generic matrix functions, minor expansions, Laplace Expansion Theorem, Cauchy-Binet Theorem, permanents, determinants, tensor algebra, matrices with non-commuting entries.     

广义换位矩阵及其应用

给出了广义换位矩阵的定义,推导出其主要性质,然后讨论了同一高维数组按不同指标索引的排列之间的相互关系,最后给出广义换位矩阵在矩阵半张量积和张量场中的应用.     

Duality for Convex Monoids

Every C*-algebra gives rise to an effect module and a convex space of states, which are connected via Kadison duality. We explore this duality in several examples, where the C*-algebra is equipped with the structure of a finite-dimensional Hopf algebra. When the Hopf algebra is the function algebra or group algebra of a finite group, the resulting state spaces form convex monoids. We will prove that both these convex monoids can be obtained from the other one by taking a coproduct of density matrices on the irreducible representations. We will also show that the same holds for a tensor product of a group and a function algebra.     

矩阵张量积不可约性的表征

为矩阵A与B的张量积,记为C=A(?)B。 定义Ⅰ设A=(a_(ij))∈C~(n×n),B=(b_(ij))∈C~(m×m)。若A在某位置(f,f)之非零元素链中有一个含r_1个A中的非零元:A(f,f)=a_(fe_1)a_((e_1)(e_2)…a_(e_r))(?),B在某位置(t,t)之非零元素链中有一个含r_2个B中的非零元:B(t,t)=b_((ts_1))b_((s_1s_2))…bs_(s_r_2-1)l,且(r_1,r_2)=1,1≤f≤n,1≤r≤m,则称A,B满足弱链条件。     

Least Squares Solution of Bivariate Surface Fitting Problems Using Tensor Product Splines

The paper treats bivariate surface fitting problems, where the data points lie on lines parallel to one of the axes. The associated bivariate collocation matrix is investigated as a block Kronecker product of univariate collocation matrices. Based on various properties of this block Kronecker product, such scattered data are characterized where the associated interpolation problem using tensor product splines admits a unique solution.     

Finite dimensional quantum Teichmüller space from the quantum torus at root of unity

Representation theory of the quantum torus Hopf algebra, when the parameter q is a root of unity, is studied. We investigate a decomposition map of the tensor product of two irreducibles into the direct sum of irreducibles, realized as a ‘multiplicity module’ tensored with an irreducible representation. The isomorphism between the two possible decompositions of the triple tensor product yields a map T between the multiplicity modules, called the 6j-symbols. We study the left and right dual representations, and correspondingly, the left and right representations on the Hom spaces of linear maps between representations. Using the isomorphisms of irreducibles to left and right duals, we construct a map A on a multiplicity module, encoding the permutation of the roles of the irreducible representations in the identification of the multiplicity module as the space of intertwiners between representations. We show that T and A satisfy certain consistency relations, forming a Kashaev-type quantization of the Teichmüller spaces of bordered Riemann surfaces. All constructions and proofs in the present work use only plain representation theoretic language with the help of the notions of the left and the right dual and Hom representations, and therefore can be applied easily to other Hopf algebras for future works.     

Monotonicity preserving representations of non-polynomial surfaces

We prove that, in contrast to the case for rational surfaces, some tensor product representations through spaces containing algebraic, trigonometric and hyperbolic polynomials are monotonicity preserving. The surface representations provided in this paper are the only known monotonicity preserving surfaces in addition to the tensor product Bézier and tensor product B-spline surfaces.     

Tensor products of direct sums

A similar formula to the one established by Ansemil and Floret for symmetric tensor products of direct sums is proved for alternating and Jacobian tensor products. It is then applied to stable spaces where a number of isomorphisms between spaces of tensors or multilinear forms are unveiled. A connection between these problems and irreducible group representations is made.     

Tensor product characterizations of mixed intersections of non quasianalytic classes and kernel theorems

Mixed intersections of non quasi‐analytic classes have been studied in [12]. Here we obtain tensor product representations of these spaces that lead to kernel theorems as well as to tensor product representations of intersections of non quasi‐analytic classes on product of open or of compact sets (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Laplacian of a Graph as a Density Matrix: A Basic Combinatorial Approach to Separability of Mixed States

We study entanglement properties of mixed density matrices obtained from combinatorial Laplacians. This is done by introducing the notion of the density matrix of a graph. We characterize the graphs with pure density matrices and show that the density matrix of a graph can be always written as a uniform mixture of pure density matrices of graphs. We consider the von Neumann entropy of these matrices and we characterize the graphs for which the minimum and maximum values are attained. We then discuss the problem of separability by pointing out that separability of density matrices of graphs does not always depend on the labelling of the vertices. We consider graphs with a tensor product structure and simple cases for which combinatorial properties are linked to the entanglement of the state. We calculate the concurrence of all graphs on four vertices representing entangled states. It turns out that for these graphs the value of the concurrence is exactly fractional. Received July 28, 2004     

关于矩阵张量积的一类问题

本文给出有限个矩阵张量积分别是正规矩阵、厄米特矩阵、正定矩阵的条件．推广了Y．E．Kuo的相关结果．另外也给出了两个亚半正定矩阵的张量积还是亚半正定矩阵的充要条件．     

Tractability of approximating multivariate linear functionals

We review selected tractability results for approximating linear tensor product functionals defined over reproducing kernel Hilbert spaces. This review is based on Volume II of our book Tractability of Multivariate Problems. In particular, we show that all nontrivial linear tensor product functionals defined over a standard tensor product unweighted Sobolev space suffer the curse of dimensionality and therefore they are intractable. To vanquish the curse of dimensionality we need to consider weighted spaces, in which all groups of variables are monitored by weights. We restrict ourselves to product weights and provide necessary and sufficient conditions on these weights to obtain various kinds of tractability.     

Self-adjoint extensions of commuting Hermite operators

It is proved that it is possible to commuting self-adjoint operators two formally commuting Hermite operators, one of which is self-adjoint after closure and the other has equal defect numbers. The operators act in a Hilbert space constructed from the tensor product of two Hilbert spaces by completion with respect to a norm defined by a positive definite kernel which satisfies a certain majorizability condition. The result can be applied to a problem of integral representations and extensions of positive definite kernels.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 5, pp. 695–697, May, 1990.     

The bialternate matrix product revisited

The well known bialternate product of two square matrices is re-examined together with another matrix product defined by means of the permanent function and having similar properties. Old and new results concerning both products are presented in a unified manner. A simple and elegant relation with the Kronecker product of matrices is also given.     

A General Multiresolution Method for Fitting Functions on the Sphere

In [7], Lyche and Schumaker have described a method for fitting functions of class C ¹ on the sphere which is based on tensor products of quadratic polynomial splines and trigonometric splines of order three associated with uniform knots. In this paper, we present a multiresolution method leading to C ²-functions on the sphere, using tensor products of polynomial and trigonometric splines of odd order with arbitrary simple knot sequences. We determine the decomposition and reconstruction matrices corresponding to the polynomial and trigonometric spline spaces. We describe the general tensor product decomposition and reconstruction algorithms in matrix form which are convenient for the compression of surfaces. We give the different steps of the computer implementation of these algorithms and, finally, we present a test example.