简单图圈基长度的最大值

图的圈基是图的一个重要结构，一个圈基的长度是该圈基中所有圈的长度之和，本讲座了简单图的圈基长度的最大值，得到了如下结果：设基圈数为k，顶点数为n的简单图的圈基长度最大值为C^*,i)若k≥4且n ≥k 2时，C^*-kn；Ⅱ）若k=2,3,则对任意n≥4，C^*=kn-1,Ⅲ）若n(n≥5）为奇数，则对k(k≥4）的所有可能值，C^*=kn。     

曲面上图的短圈结构与Mohar和Thomassen的一个问题的解决

研究了(赋权)图的圈基结构并且对包含在最小圈基中的短圈提供了大量信息. 建立了一个基变换的Hall型定理, 利用此定理, 给出了判断一个圈基是最小圈基的充分必要条件, 而且，证明了一个(赋权)图的最小圈基结构是唯一的. 这一性质对于最大圈基也成立 (尽管在最小圈基方面已有很多工作, 而在最大圈基方面的工作几乎没有). 利用这些方法， 发现了(赋权)图中具有特定性质的短圈的一些新结果. 作为应用， 决定了一个嵌入图的短圈的结构, 并找到一个多项式算法能够判断一个嵌入图中是否存在双侧圈, 如果这样的圈存在, 就可以找到一个最短的双侧圈. 这回答了B. Mohar和C. Thomassen提出的一个未解决问题, 并对他们提出的另一个未解决问题给出了部分解答.     

修正冒泡排序网络的边偶泛圈性

对于一个二部图G,如果在G中存在任意长为偶数l(4≤l≤|V(G)|)的圈,则称这个二部图G是偶泛圈的:如果对G中任意一边e,在G中存在任意长为偶数l(4≤l≤|V(G)|)且包含e的圈,则称这个二部图G是边偶泛圈的.修正冒泡排序网络是互连网络中的一个重要的Cayley图模型.在此,证明了对任意的自然数n,当n≥3时,修正冒泡排序网络Y_n是偶泛圈的,同时也是边偶泛圈的.     

两个不交图的联图的最小圈基长度

这篇文章中,我们分两种情形分别给出了计算两个不交图的联图的最小圈基长度的公式.作为它们的应用,我们给出了计算n个相同的图的联图以及完全r-部图等图的最小圈基长度的公式.     

由圈长分布确定的偶图

阶为n的图G的圈长分布是序列(C1，C2，…，Cn)，其中ci是图G中长为i的圈数．本文得到如下结果：设A∈_E(Kn,r)，|A|≤1，且n≤r≤min{n 6，2n-3)，则G=Kn,r，r-A是由它的圈长分布确定的．     

联图的圈基

MacLane于1937年给出了圈基方面的重要定理: 图G是平面图, 当且仅当图G有2-重基. 连通图G_1和G_2的联图G_1\vee G_2指的是在它们的不交并G_1\bigcup G_2上添加边集(u,v)|u\in V(G_1), v\in V(G_2). 对G_1和G_2的联图G_1\vee G_2的圈基重数进行了研究, 得到了一个上界, 改进了Zare的结果. 并在此基础之上, 进一步得到特殊联图C_m\vee C_n的圈基重数的一个上界.     

关于3正则图的三匹配交猜想(Ⅰ)

Fan和Raspaud 1994年提出如下猜想任一无桥3正则图必有三个交为空集的完美匹配. 本文研究一类特殊的无桥3正则图G存在图G的一个完美匹配M1使得G-M1恰含有两个奇圈和若干偶圈. 在偶圈数≤2的情形以及在偶圈数≤4且G是圈4-边连通的情形,本文证明了一定存在图G的两个完美匹配M2和M3使得M1∩M2∩M3=φ.     

关于3正则图的三匹配交猜想（I）

Fan和Raspaud1994年提出如下猜想：任一无桥3正则图必有三个交为空集的完美匹配。本研究一类特殊的无桥3正则图G：存在图的G的一个完美匹配M1使得G－M1恰含有两个奇圈和若干偶圈。在偶圈数≤2的情形以及在偶圈数≤4且G是圈4－边连通的情形，本证明了一定存在图G的两个完善匹配M2和M3使得M1∩M2∩M3＝φ。     

给定最大度的单圈偶图的谱半径

单圈偶图是边数等于顶点数的简单连通偶图.Δ（G）表示图G的最大度.文中给出了最大度为Δ(≥ⁿ⁺¹/2)的n阶单圈偶图的谱半径的上界,并刻画了达到该上界的图.文中还证明了当Δ（G）≥[（2n+1）/3]+1时,n（≥8）阶单圈偶图G的谱半径随着最大度的递增而严格递增,并在此基础上给出了谱半径排在前17位的n（≥16）阶单圈偶图.     

偶图Kn,r-A(|A|≤3)的圈长分布唯一性

阶为n的图G的圈长分布是序列(c_1,c_2,…,c_n),其中c_i是图G中长为i的圈数。设A(?)E(K_(n,r))。本文得到如下结果：若|A|=2,且n≤r≤min{n 6,2n-5),则G=K_(n,r)-A是由它的圈长分布确定的；若|A|=3,且n≤r≤min{n 6,2n-7),则G=K_(n,r)-A也是由它的圈长分布确定的。     

A new characterization of dual bases in finite fields and its applications

We propose a new characterization of dual bases in finite fields. Let A=(α₁,…,α_n) be a basis of F over F_q and its dual basis B=(β₁,…,β_n) with the transition matrix C∈GL_n(F_q) such that (β₁,…,β_n)=(α₁,…,α_n)C. We show that holds for all 1?k?n, where T_k∈M_n(F_q) satisfies α_k(α₁,…,α_n)=(α₁,…,α_n)T_k. Conversely, suppose F=F_q(α_k^′) and for some 1?k^′?n and G∈GL_n(F_q), then B is equivalent to (α₁,…,α_n)G. As applications, we can construct the dual basis of a given basis A or determine whether the dual basis of A satisfies the desired conditions from T_k. This generalizes the results obtained by Liao and Sun for normal bases. Furthermore, we give a simple proof of the theorem of Gollmann, Wang and Blake for polynomial bases.     

A representation theorem for Schauder bases in Hilbert space

A sequence of vectors in a separable Hilbert space is said to be a Schauder basis for if every element has a unique norm-convergent expansion

If, in addition, there exist positive constants and such that

then we call a Riesz basis. In the first half of this paper, we show that every Schauder basis for can be obtained from an orthonormal basis by means of a (possibly unbounded) one-to-one positive self adjoint operator. In the second half, we use this result to extend and clarify a remarkable theorem due to Duffin and Eachus characterizing the class of Riesz bases in Hilbert space.

     

Minimal and maximal unconditional bases with respect to framings

This paper studies framings in Banach spaces, a concept raised by Casazza, Han and Larson, which is a natural generalization of traditional frames in Hilbert spaces and unconditional bases in Banach spaces. The minimal unconditional bases and the maximal unconditional bases with respect to framings are introduced. Our main result states that, if （xi, fi） is a framing of a Banach space X, and （eimin） and （eimax） are the minimal unconditional basis and the maximal unconditional basis with respect to （xi, fi）, respectively, then for any unconditional basis （ei） associated with （xi, fi）, there are A,B 〉 0 such that A｜｜i=1∑∞aieimin｜｜≤｜｜i=1∑∞aiei｜｜≤B｜｜i=1∑∞aieimax｜｜ for all （ai） ∈ c00.
It means that for any framing, the corresponding associated unconditional bases have common upper and lower bounds.     

Orthonormal bases associated with multi-knot piecewise linear function sequences on [0, 1)<Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>

We investigate two classes of orthonormal bases for L^2（[0, 1）^n）. The exponential parts of those bases are multi-knot piecewise linear functions which are called spectral sequences. We characterize the multi-knot piecewise linear spectral sequences and give an application of the first class of piecewise linear spectral sequences.     

The quantum general linear supergroup,canonical bases and Kazhdan-Lusztig polynomials

Canonical bases of the tensor powers of the natural -module V are constructed by adapting the work of Frenkel, Khovanov and Kirrilov to the quantum supergroup setting. This result is generalized in several directions. We first construct the canonical bases of the ℤ₂-graded symmetric algebra of V and tensor powers of this superalgebra; then construct canonical bases for the superalgebra O _q (M _m|n ) of a quantum (m,n) × (m,n)-supermatrix; and finally deduce from the latter result the canonical basis of every irreducible tensor module for by applying a quantum analogue of the Borel-Weil construction. This work was supported by National Natural Science Foundation of China (Grant No. 10471070)     

On the Restricted Order of Asymptotic Bases of Order Two

The restricted order of an asymptotic basis A is the least integer h, if it exists, such that every sufficiently large integer is the sum of h or fewer distinct elements of A. We show that any asymptotic basis of order 2 has a restricted order at most equal to 4. We also provide an example of an additive basis of order 2 whose restricted order is 4.To Jean-Louis Nicolas2000 Mathematics Subject Classification: Primary—11B13     

Characterizations of multi-knot piecewise linear spectral sequences

We study two classes of orthonormal bases for in this paper. The exponential parts of these bases are multi-knot piecewise linear functions. These bases are called spectral sequences. Characterizations of these multi-knot piecewise linear functions are provided. We also consider an opposite problem for single-knot piecewise linear spectral sequences, where the piecewise linear functions are defined on and . We show that such spectral sequences do not exist except for . *Supported by the Technology and Research project 2002YF015 of the Ministry of Railway of China and by the Natural Science Foundation of China under grant 10371122. **Supported by the Presidential Foundation of Graduate School of the Chinese Academy of Sciences (yzjj200505).     

The formulae and algorithms for Lagrange-power basis transformation and Lagrange-Newton transformation

The interpolation polynomials based on Lagrange, Newton and power basis play important roles in applied mathematics, computing method and many other emerging applications. In this paper, we present some coordinate transformation formulae and algorithms as demonstrated below. Firstly, we put forward the formulae of the Lagrange-power basis transformation and its inverse transformation, and as a byproduct, we provide a new method to arrive at the inversion of the Vandermonde matrix. Secondly, we give the formulae of Lagrange-Newton transformation and its inverse transformation. Moreover, we construct related algorithms of Lagrange-power basis transformation, Lagrange-Newton transformation and their inverse transformations.     

The Basis Number of Some Special Non-Planar Graphs

The basis number of a graph G was defined by Schmeichel to be the least integer h such that G has an h-fold basis for its cycle space. He proved that for m, n 5, the basis number b(K _m,n ) of the complete bipartite graph K _m,n is equal to 4 except for K _6,10, K _5,n and K _6,n with n = 5, 6, 7, 8. We determine the basis number of some particular non-planar graphs such as K _5,n and K _6,n , n = 5, 6, 7, 8, and r-cages for r = 5, 6, 7, 8, and the Robertson graph.     

Banach空间上的框架与拟Riesz基

该文首先给出Ｂａｎａｃｈ空间上的框架与拟Ｒｉｅｓｚ基的充要条件,其次讨论Ｂａｎａｃｈ空间上的框架和拟Ｒｉｅｓｚ基的稳定性,特别地,讨论在Ｂａｎａｃｈ空间上关于框架与拟Ｒｉｅｓｚ基的广义Ｐａｌｅｙ Ｗｉｅｎｅｒ定理．