张量对称类上诱导算子的y-数值半径(英文)

本文研究了诱导矩阵K(A)的y-数值半径ry(K(A))、y-可分数值半径ryχ(K(A))与范数A2、广义矩阵函数dχG(A)之间的关系问题.利用ry(K(A))及ryχ(K(A))的概念,得到了ry(K(A))、ryχ(K(A))、‖A‖2、dGχ(A)它们之间的两个不等式.     

由自共轭线性微分算子所确定的函数类在Lq(T)中的相对宽度

得到了使等式Kn(K2(Pr),MK2(Pr),L2(T))=dn(K2(Pr),L2(T))成立的最小M值,并计算了Kn(K2(Pr),K2(Pr),Lq(T))的渐近阶,其中Kn(.,.,Lq(T))和dn(.,Lq(T)),1≤q≤∞,分别代表Kolmogorov意义下在Lq(T)中的相对宽度和宽度,K2(Pr)表示定义在[-π,π]上由自共轭线性微分算子所确定的光滑函数类.     

分次Morita Contexts与分次根

设M={A=⊕_(g∈G)A_g,V=⊕_(g∈G)V_g,W=⊕_(g∈G)W_g,B=⊕_(g∈G)B_g}与(,),[,]是一个G-分次Morita Context,且满足(V,W)=A,[W,V]=B,A,B都有单位元．本文证明τG(B)：[W,ΥG(A)V]=【WΥc(A),V],ΥG(A)=(V,ΥG(B)W)=(VΥG(B),W)其中ΥG代表P_G(分次素根),J_G(分次Jacobson根),K_G(分次Koethe根),L_G(分次Levitzki根)和s_G(分次强素根),us_G(分次一致强素根)．     

有向图的拉普拉斯谱半径的几个上界

设G=(V(G),E(G))是一个简单有向图具有顶点集V(G)={v_1,v_2,…,v_n)和弧集E(G).用d_i~+表示顶点v_i的出度.设A(G)是有向图G的邻接矩阵和D(G)=diag(d_1~+,d_2~+,…,d_n~+)有向图G的顶点出度对角矩阵,则称L(G)=D(G)-A(G)为有向图G的拉普拉斯矩阵.L(G)的谱半径称作有向图G的拉普拉斯谱半径,用A(G)表示.在这篇文章中,给出了关于A(G)的一些上界,进而一些关于λ(G)涉及有向图G的出度和二次平均出度的上界也被得到.最后,我们举例对这些上界进行了比较.     

Hilbert空间中一些二阶线性微分—算子方程的Cauchy问题及其近似解

我们讨论Hilbert空间中的二阶线性微分—算子方程在初始条件下的Cauchy问题的近似解。设(V,(·,·)_v,K)(W,(·,·)_w,K)分别为数域K(C或K)上具有内积(·,·)_v、(·,·)_w的Hilbert空间简记为V、W,相应的范数为||·||_v、||·||_w。V’、W’分别为其对偶空     

SL(2,R)上一类极大算子的(H_(∞,s)~1,L~1)型

本文我们引入了函数类B_δ(G//K)={φ一L~1(G//K||L~1(G//K)||φ(t)|≤Δ~(-1)(t)(1+t)~(1-δ),δ>0),对f∈L~p(G//K),1≤p≤∞,和极大算子M_δf(x)=sup|φ*f(x)|,证明了这类算子 >0 φ∈B_δ(G//K)是(H_∞~1,L~1)型的.     

二分(0,mf-m+1)-图的正交(0,f)-因子分解

设G=(X,Y,E(G))是一个二分图,分别用V(G)=XUY和E(G)表示G的顶点集和边集.设f是定义在V(G)上的整数值函数且对(A)x∈V(G)有f(x)≥k.设H_1,H_2,…,H_k是G的k个顶点不相交的子图,且|E(H_i)|=m,1≤i≤k.本文证明了每个二分(0,mf-m+1)-图G有一个(0,f)-因子分解正交于Hi(i=1,2,…,k).     

一类非齐次核的Hilbert型级数算子最佳搭配参数的充要条件

选择搭配参数a,b,利用权函数方法,可得核为K(m,n)的级数算子T的不等式:||T((a))||p,β(a,b) ≤ M(a,b)||(a)||p,α(a,b),(a) ={am}一般地,M(a,b)并不是T:lap(a,b)→lβp(a,b)的算子范数,针对非齐次核K(m,n)=G(mλ1/nλ2)(λ1λ2＞0)...     

图上p-Laplace算子的特征值估计

设G(V,E)为满足■(m,K)条件的连通有限图,其中p≥2,m 0,K≤0.本文在G上考虑了方程?pu=-λ_p|u|~(p-2)u解的椭圆型梯度估计,其中?_p为p-Laplace算子.作为应用,导出了G上?_p的第一非零特征值的下界估计.     

关于ρ(L_(r,w))、ρ(J_w)的最小值

本文证明了当线性方程组系数矩阵 A之 Jacobi迭代矩阵 B=L+ U≥ 0 ,ρ( B) <1时 Gauss-Seidel法之迭代矩阵 G=L1,1的谱半径 ρ( G) =ρ( L1,1)是 ρ( Lr,w) ( 0≤ r≤w≤ 1 ,w>0 )中的最小值 ,即此时 Gauss-Seidel迭代是 AOR法中收敛最快的迭代法 .并且对 JOR法 (谱半径为 ρ( Jw) )和 SAOR法也作了相应的论述 .     

一类线性变换半群的格林关系

Let V be a linear space over a field F with finite dimension, L（V） the semigroup, under composition, of all linear transformations from V into itself. Suppose that V = V1 V2 ... Vm is a direct sum decomposition of V, where V1,V2,..., Vm are subspaces of V with the same dimension. A linear transformation f ∈ L（V） is said to be sum-preserving, if for each i （1 ≤ i ≤ m）, there exists some j （1 ≤ j ≤ m） such that f（Vi） Vj. It is easy to verify that all sum-preserving linear transformations form a subsemigroup of L（V） which is denoted by L （V）. In this paper, we first describe Green＇s relations on the semigroup L （V）. Then we consider the regularity of elements and give a condition for an element in L （V） to be regular. Finally, Green＇s equivalences for regular elements are also characterized.     

Induced operators on symmetry classes of tensors

Let be an -dimensional Hilbert space. Suppose is a subgroup of the symmetric group of degree , and is a character of degree 1 on . Consider the symmetrizer on the tensor space

defined by and . The vector space

is a subspace of , called the symmetry class of tensors over associated with and . The elements in of the form are called decomposable tensors and are denoted by . For any linear operator acting on , there is a (unique) induced operator acting on satisfying

In this paper, several basic problems on induced operators are studied.

     

LIE ALGEBRA K$(n,\mu _j,m)$ OF CARTAN TYPE OF CHARACTERISTIC p=2

Let $K(n,\mu _j,m),n=2r+1$,denote the Lie algebra of characteristic p=2,which is defined in [4].In the paper the restrictability of $K(n,\mu _j,m)$ is discussed and it is proved that,when $r\equiv 1(mod 2)$ and $r>1,I(ad f)=n+1$ if and only if $0\neq f \in $. Then the invariance of some filtrations of K(n,\mu,m) and the condition of isomorphism of K(n,\mu _i,m) and K(n',\mu _j ^',m') are obtained.Besides,the generators and the derivation algebra of K(n,\mu _i,m) are discussed.The results also hold,when $r\equiv 0 (mod 2)$ and r>0.     

Volterra算子及其伴随算子线性组合的数值域

经典Volterra算子$V$及其伴随算子$V^*$在复空间$L^2[0,1]$中起着关键作用. 关于$V$和$V^*$的线性组合的性质, 我们给出了确保$z_1V+z_2V^*(z_1,z_2\in\mathbb{C})$满足增生性质的等价条件. 本文描述了$(u+iv)I+mV+nV^*(u,v,m,n\in\mathbb{R},m+n\geq0)$数值域的精确表示.     

单圈图的无符号狄利克雷谱半径

Let G be a simple connected graph with pendant vertex set ?V and nonpendant vertex set V_0. The signless Laplacian matrix of G is denoted by Q(G). The signless Dirichlet eigenvalue is a real number λ such that there exists a function f ≠ 0 on V(G) such that Q(G)f(u) = λf(u) for u ∈ V_0 and f(u) = 0 for u ∈ ?V. The signless Dirichlet spectral radiusλ(G) is the largest signless Dirichlet eigenvalue. In this paper, the unicyclic graphs with the largest signless Dirichlet spectral radius among all unicyclic graphs with a given degree sequence are characterized.     

一类带齐次核的奇异重积分算子的范数及其应用

设核函数K(u,v)具有对称性和齐次性,对如下定义的奇异重积分算子T:(Tf)(y)=∫R_+~n K(‖x‖α,‖y‖α)f(x)dx,y∈R_+~n,其中‖x‖α=(x_1~α+…+x_n~α)~1/α(α>0),研究了T的范数及其应用.     

由圈长分布确定的二部图~$K_{n,n r}-A\ (|A|\leq 3)$

The cycle length distribution of a graph G of order n is a sequence （c1 （G）,…, cn （G））, where ci （G） is the number of cycles of length i in G. In general, the graphs with cycle length distribution （c1（G） ,…,cn（G）） are not unique. A graph G is determined by its cycle length distribution if the graph with cycle length distribution （c1 （G）,…, cn （G）） is unique. Let Kn,n＋r be a complete bipartite graph and A lohtaib in E（Kn,n＋r）. In this paper, we obtain： Let s 〉 1 be an integer. （1） If r = 2s, n 〉 s（s - 1） ＋ 2｜A｜, then Kn,n＋r - A （A lohtain in E（Kn,n＋r）,｜A｜ ≤ 3） is determined by its cycle length distribution; （2） If r = 2s ＋ 1,n 〉 s^2 ＋ 2｜A｜, Kn,n＋r - A （A lohtain in E（Kn,n＋r）, ｜A｜ ≤3） is determined by its cycle length distribution.     

最大度与最小度相差不超过2的图的平衡judicious划分

图G的顶点集V(G)的一个二部划分V_1和V_2叫做平衡二部划分,如果||V_1|-|V_2||≤1成立.Bollobas和Scott猜想:每一个有m条边且最小度不小于2的图,都存在一个平衡二部划分V_1,V_2,使得max{e(V_1),e(V_2)}≤m/3,此处e(V_i)表示两顶点都在V_i(i=1,2)中的边的条数.他们证明了这个猜想对正则图(即△(G)=δ(G))成立.颜娟和许宝刚证明了每个(k,k-1)-双正则图(即△(G)-δ(G)≤1)存在一个平衡二部划分V_1,V_2,使得每一顶点集的导出子图包含大约m/4条边.这里把该结论推广到最大度和最小度相差不超过2的图G.     

Shift Generated Haar Spaces on Compact Domains in the Complex Plane

Haar spaces are certain finite-dimensional subspaces of $\cc(K)$, where $K$ is a compact set and $\cc(K)$ is the Banach space of continuous functions defined on $K$ having values in $\C$. We characterize those Haar spaces which are generated by shifts applied to a single, analytic function for $K\subset\C$. This means that an arbitrary finite number of shifts generates Haar spaces by forming linear hulls. We have to distinguish two cases: (a) $K\not=\overline{K^\circ}$; (b) $K=\overline{K^\circ}$. It turns out that, in case (a), an analytic Haar space generator for dimensions one and two is already a universal Haar space generator for all dimensions. The geometrically simplest case that, in case (b), $K$ is convex with smooth boundary turns out to be the most difficult case. There is one numerical example in which the entire function $f:=1/\Gamma$ is interpolated in a shift generated Haar space of dimension four.     

缺项算子矩阵的本性谱

Let =(A C X B)be a 2×2 operator matrix acting on the Hilbert space н( )κ.For given A ∈B (H),B ∈B(K)and C ∈B(K,H)the set Ux∈B(H,к)σe(Mx)is determined,where σe(T)denotes the essential spectrum.