对角量子信道的纠错码空间的存在性与构造

通过量子信道的Kraus算子,提出了对角量子信道的概念,证明了对角量子信道的一些性质：一个量子信道成为对角量子信道的充要条件是所有对角矩阵都是它的不动点;同一对角量子信道的所有压缩矩阵具有相同的秩;一个对角量子信道不可纠错的充要条件是其压缩矩阵是行满秩的.进而证明了一个对角量子信道在整个空间上可纠错当且仅当其压缩矩阵为1秩阵.最后,利用一个具体例子给出了构造对角量子信道的码空间的一种方法.     

矩阵对角占优性的推广

本文引入了一类新的对角占优矩阵，并讨论了它与Ｄ０（Ｒ），ＳＤ０（Ｒ）类矩阵的关系．     

矩阵块对角占优性的推广及应用

在本文中,我们给出了一类块对角占优矩阵的定义,讨论了块对角占优矩阵的判定及应用,相应的结果改进和推广了[1]—[4]中的若干结论.     

块对角占优性的推广与特征值分布

本文引入了若干矩阵块对角占优性概念，并利用Ｎｏｗｏｓａｄ和Ｈｏｆｆｍａｎ提出的Ｇ－ｂｉｂ ｏｖｔ ｓｖ。     

矩阵对角占优性的推广及应用

§1.引言设 A=(a_(ij))_(n×n)为一复矩阵,若有一正向量 d=(d_1,d_2,…,d_n)~T 使得d_i|a_(ij)|≥sum from j≠1 d_j|a_(ij)|,(1)对每一 i∈N={1,2,…,n}都成立,则称 A 为广义对角占优矩阵,记为 A∈D_0~*;如若(1)式中每一不等号都是严格的,则称 A 为广义严格对角占优矩阵,记为 A∈D~*.特别地,当 d=(1,1,…,1)~T 时,A∈D_0~*及 A∈D~*即是通常的对角占优与严格对角占优,分别记作 A∈D_0及 A∈D.利用矩阵的对角占优性质讨论其特征值分布是矩阵论中的重要课题,文献[5]—[10]给出了这方面的重要结果.n 阶实方阵 A 称为 M-矩阵,如果 A具有形式:A=sI-B,s>ρ(B),其中 B 为 n 阶非负方阵,ρ(B)表 B 之谱半径,利用广义严格对角占优的概念,文[1]给出了 M-矩阵的等价表征:若 n 阶实方阵     

渐近好pm-ary量子码的构造

对任意素数P及自然数m,用代数几何码构造了一列渐近好的pm-ary量子纠错码.     

非广义对角占优矩阵的判定准则

给出了判定非广义对角占优矩阵的充要条件,从理论上彻底解决了不可约非广义对角占优矩阵的判定问题,并给出了判定不可约非广义对角占优矩阵的具体算法.     

广义对角占优矩阵的判定

利用α-对角占优矩阵的性质,给出了判定广义对角占优矩阵的几个充分条件,改进了近期的一些结果,并用相应的数值实例说明了这些结果的有效性.     

广义对角占优矩阵的充分条件

给出了一类局部双对角占优矩阵,进而获得了几个新的广义对角占优矩阵的充分条件.     

交叉对角化TOeplitz预条件子的构造空间

1 问题的提出一个n阶方阵Tn被称为Toeplitz矩阵,如果它满足     

Approximative Properties of Diagonal Operators in Orlicz Spaces

We obtain the exact values of some important approximative quantities (such as the best approximation, the basis width, Kolmogorov's width, and the best n-term approximation) of certain sets of images of the diagonal operators in the Orlicz sequence spaces l _M .     

Entropy Numbers of Diagonal Operators between Vector-Valued Sequence Spaces

Upper and lower bounds are established for the entropy numbersof certain diagonal operators between Banach sequence spaces.These diagonal operators are isomorphisms between the spacesconsidered in the paper and weighted sequence spaces consideredby Leopold so that the entropy numbers in question coincidewith those considered by Leopold. The results in the paper improvethe previous results in at least two ways. The estimates inthe paper are ‘almost’ sharp in the sense that theupper and lower estimates differ only by logarithmic factorsfor a much wider range of parameters. Moreover, all the upperestimates are improvements on the previous ones, the improvementbeing quite significant in some cases.     

Almost Diagonal Matrices and Besov-Type Spaces Based on Wavelet Expansions

This paper is concerned with problems in the context of the theoretical foundation of adaptive algorithms for the numerical treatment of operator equations. It is well-known that the analysis of such schemes naturally leads to function spaces of Besov type. But, especially when dealing with equations on non-smooth manifolds, the definition of these spaces is not straightforward. Nevertheless, motivated by applications, recently Besov-type spaces \(B^\alpha _{\Psi ,q}(L_p(\Gamma ))\) on certain two-dimensional, patchwise smooth surfaces were defined and employed successfully. In the present paper, we extend this definition (based on wavelet expansions) to a quite general class of d-dimensional manifolds and investigate some analytical properties of the resulting quasi-Banach spaces. In particular, we prove that different prominent constructions of biorthogonal wavelet systems \(\Psi \) on domains or manifolds \(\Gamma \) which admit a decomposition into smooth patches actually generate the same Besov-type function spaces \(B^\alpha _{\Psi ,q}(L_p(\Gamma ))\), provided that their univariate ingredients possess a sufficiently large order of cancellation and regularity. For this purpose, a theory of almost diagonal matrices on related sequence spaces \(b^\alpha _{p,q}(\nabla )\) of Besov type is developed.     

Coorbits of Quantum Homogeneous Spaces

The notion of coorbits for spaces with quantum group actions is introduced. A space with a quantum group action is given by a pair of algebras: an associative algebra which is the analog of a classical topological space, and a Hopf algebra which is the analog of a classical topological group. The Hopf algebra acts on the associative algebra via a comodule structure mapping which is also an algebra homomorphism. For a space with a quantum group action, a coorbit is a pair of spaces given by the image and the kernel of an algebra homomorphism from the associative algebra to the Hopf algebra. The coorbits of several types of quantum homogeneous spaces are discussed. In the case when the associative algebra is the group algebra of a group and the Hopf algebra is a quotient of the group algebra, the connection between the set of coorbits and the character group is established.     

二元码M_q(n,d,k)的检错性和纠错性

二元码Mq(n,d,k)是一个非适应性分组测试(NGT)算法的数学模型,是一个d-disjunct矩阵.二元码的汉明距离(Hamming)决定着码的检错性和纠错性,通过计算二元码Mq(n,d,k)的汉明距离,得到了它的检错性和纠错性.     

Quantum Groups and the Genetic Code

The quantum algebra in the limit q 0 is proposed as a symmetry algebra for the genetic code. The nucleotide triplets (codons) in the DNA chain are classified in crystal bases. This construction can be compared to the baryon classification from quarks in particle physics, one main difference being the natural order in the state constituents provided by the crystal base. An operator ensuring the correspondence between codons and amino acids is constructed from the above algebra: two codons corresponding to the same or different amino acids acquire the same or different eigenvalues respectively. Then a set of relations between the physicochemical properties of the amino acids are derived and compared with the experimental data. Correlations of the codon usage for quartets and sextets are determined, fitting naturally in the framework of this model.     

Quantum Cohomology of Minuscule Homogeneous Spaces

We study the quantum cohomology of (co)minuscule homogeneous varieties under a unified perspective. We show that three points Gromov–Witten invariants can always be interpreted as classical intersection numbers on auxiliary varieties. Our main combinatorial tools are certain quivers, in terms of which we obtain a quantum Chevalley formula and a higher quantum Poincaré duality. In particular, we compute the quantum cohomology of the two exceptional minuscule homogeneous varieties. DOI: .     

Analytic Rank of Graph Algebras and Quantum Spaces

We show that the analytic rank, as defined by Murphy, of a unitalgraph C*-algebra is either 1 or 0, depending on whether or notthe underlying graph possesses an initial loop. As a corollary,we show that the analytic rank of certain quantum spaces (includingsome quantum spheres, projective spaces and lens spaces) is1. 2000 Mathematics Subject Classification 46L05, 46L65, 46L87.     

Existence and Stability of Even-dimensional Asymptotically de Sitter Spaces

A new proof of Friedrich’s theorem on the existence and stability of asymptotically de Sitter spaces in 3 + 1 dimensions is given, which extends to all even dimensions. In addition we characterize the possible limits of spaces which are globally asymptotically de Sitter, to the past and future. Communicated by Sergiu Klainerman submitted 30/08/04, accepted 27/01/05