双曲空间中完备子流形的特征值估计

研究了$(n+p)$维双曲空间$\mathbb{H}^{n+p}$中完备非紧子流形的第一特征值的上界.特别地,证明了$\mathbb{H}^{n+p}$中具有平行平均曲率向量$H$和无迹第二基本形式有限$L^q(q\geq n)$范数的完备子流形的第一特征值不超过$\frac{(n-1)^2(1-|H|^2)}{4}$,和$\mathbb{H}^{n+1}(n\leq5)$中具有常平均曲率向量$H$和无迹第二基本形式有限$L^q(2(1-\sqrt{\frac{2}{n}})相似文献   

一类二元关系的公共后继指数集

设$V=\{ a_{1},a_{2},\ldots ,a_{n}\}$是$n\geq 2$的一个有限集合,$V$上所有本原的二元关系组成的集合记为$P_{n}(V)$.对任意的$Q\in P_{n}(V)$,与$Q$对应的有向图记为$G(Q)$.记$ P_{n}(V,d)=\{Q:Q\in P_{n}(V)$ 且$G(Q)$ 恰好包含 $d$ 个环\},其中$0相似文献   

Clifford 环面 Sm(\sqrt{\frac{m}{n}})×Sn-m(\sqrt{\frac{n-m}{n}})的刚性定理

\small\zihao{-5}\begin{quote}{\heiti 摘要:} 设$M$为$n+1$维单位球面$S^{n+1}(1)$中的一个极小闭超曲面，如果 $ n \le S \le n+\frac{2}{3}$, 则有 $S=n$ 且 $M$ 与某一Clifford 环面 $S^m(\sqrt{m/n}) \times S^{n-m}(\sqrt{(n-m)/n})$等距.     

Young表与$\textrm{U}_{q}(\mathrm{osp}(1|2n))$的晶体基

设 $U_q(\mathrm{osp}(1|2n))$是对应Lie超代数$\mathrm{osp}(1|2n)$的量子包络超代数. 利用满足一定条件的半标准Young表, 给出有限维既约$U_q(\mathrm{osp}(1|2n))$模晶体图的实现 . 建立晶体图张量积分解的广义Littlewood-Richardson法则.     

粗糙核分数次积分算子的多线性算子在Hardy空间上的有界性

该文证明带有粗糙核的分数次积分算子的多线性算子\[T_{\Omega,\alpha}^{A}(f)(x)={\rm {\rm p.v.}}\int_{R^{n}}P_{m}(A;x,y)\frac{\Omega(x-y)}{|x-y|^{n-\alpha+m-1}}f(y){\rm d}y\]的$(H^{1}(\rr^{n}),L^{\frac{n}{n-\alpha},\infty}(\rr^{n}))$有界性.     

由H\"{o}rmander向量场构成的抛物方程的 $W_{\ast}^{1,p}$ 正则性

设 $X_{1},\cdots ,X_{q}\ (q相似文献   

图的上可嵌入性与围长及相邻顶点度和

$G$是一个阶为$n$围长为$g$的简单图, $u$和$v$是$G$中任意两个相邻顶点, 如果$d_{G}(u)$ + $d_{G}(v)$ $\geq$ $n - 2g + 5$, 则$G$是上可嵌入的; 如果$G$是2-\!边连通(或3-\!边连通)图, 则当 $d_{G}(u)$ + $d_{G}(v)$ $\geq$ $n - 2g + 3$ (或 $d_{G}(u)$ + $d_{G}(v)$ $\geq$ $n - 2g - 5$)时$G$是上可嵌入的, 并且上面3个下界都是紧的.     

顶点算子超代数的双模

对于任意一个顶点算子超代数$V$及$m,n\in
\frac{1}{2}\mathbb{Z}_{+}$, 通过构造$A_n(V)-A_m(V)$-\!双模
$A_{n,m}(V)$, 刻画了$V$
的一个从可容许$V$-\!模的第$m+1$层子空间到第$n+1$层子空间的作用,
并得到一类Verma型可容许$V$-\!模.     

关于域的K2群的挠

设$F$是域, 记 $G_{n}(F)=\{\{a,
\Phi_{n}(a)\} \in K_{2}(F)\mid {a, \Phi_{n}(a)} \in F^{*}\},$
这里$\Phi_{n}(x)$ 是$n$次分圆多项式. 首先,
使用关于数域上的Mordell猜想的Faltings定理证明了若$F$是数域, $n\neq
1, 4, 8, 12$且含有平方因子, 则$G_{n}(F)$不是$K_{2}(F)$的子群; 然后,
使用Manin, Grauert, Samuel和李克正关于
函数域上的Mordell猜想的结果, 对代数闭域上的函数域证明了类似的结果.     

Almost Periodic Linear System and Exponential Dichotomies (in English)

本文讨论概周期线性系统具有指数型二分法和它的特征指数的关系。 考虑线性系统 $\[\frac{{dx}}{{dt}} = A(t)x\]$ （1） 其中A(t)是n*n方阵，它在实轴上连续和有界。如果（1）有基本方阵X(t)，具有如下的分解 $\[X(t) = {X_1}(t) + {X_2}(t),{X^{ - 1}}(s) = {Z_1}(s) + {Z_2}(s)\]$ $\[X(t){X^{ - 1}}(s) = {X_1}(t){Z_1}(s) + {X_2}(t){Z_2}(s)\]$ 同时有常数 \alpha ,\beta >0,使 $\[||{X_1}(t){Z_1}(s)|| \le \beta exp( - \alpha (t - s)),t \ge s\]$ $\[||{X_2}(t){Z_2}(s)|| \le \beta exp(\alpha (t - s)),s \ge t\]$ 就说（1）具有指数型二分法。 我们所得的结果，可叙述如下： 一、对拟周期线性系统，存在同频率的酉变换，把它化为三角型系统。从而推出： 若拟周期线性系统的特征指数异于零，则它具有指数型二分法。 二、对概周期线性系统，定了广义的零特征指数。当它不具有广义的零特征指数，则该系统具有指数型二分法。 三、利用一和二的结果，解决了Hale所提的关于中心积分流形的存在性问题。     

常曲率空间中具正Ricci曲率的子流形

设S~(n+p)(1)是一单位球面,M~n是浸入S~(n+p)(1)的具有非零平行平均曲率向量的n维紧致子流形.证明了当n≥4,p≥2时,如果M~n的Ricci曲率不小于(n-2)(1+H~2),则M~n是全脐的或者M~n的Ricci曲率等于(n-2)(1+H~2),进而M~n的几何分类被完全给出.     

Generalized Ejiri''s Rigidity Theorem for Submanifolds in Pinched Manifolds

Let $M^{n}(n\geq4)$ be an oriented compact submanifold with parallel mean curvature in an $(n+p)$-dimensional complete simply connected Riemannian manifold $N^{n+p}$. Then there exists a constant $\delta(n,p)\in(0,1)$ such that if the sectional curvature of $N$ satisfies $\ov{K}_{N}\in[\delta(n,p), 1]$, and if $M$ has a lower bound for Ricci curvature and an upper bound for scalar curvature, then $N$ is isometric to $S^{n+p}$. Moreover, $M$ is either a totally umbilic sphere $S^n\big(\frac{1}{\sqrt{1+H^2}}\big)$, a Clifford hypersurface $S^{m}\big(\frac{1}{\sqrt{2(1+H^2)}}\big)\times S^{m}\big(\frac{1}{\sqrt{2(1+H^2)}}\big)$ in the totally umbilic sphere $S^{n+1}\big(\frac{1}{\sqrt{1+H^2}}\big)$ with $n=2m$, or $\mathbb{C}P^{2}\big(\frac{4}{3}(1+H^2)\big)$ in $S^7\big(\frac{1}{\sqrt{1+H^2}}\big)$. This is a generalization of Ejiri''s rigidity theorem.     

对偶均值积分的Marcus-Lopes不等式

Milman曾提出过一个问题;在混合体积理论,是否存在Marcus-Lopes型和Bergstrom型不等式?即对R~n上任意凸体K与L且i=0,…,n-1,是否成立(W_i(K+L))/(W_i+1(K+L))≥(W_i(K))/(W_i+1(K))+(W_i(L))/(W_i+1(L))?这里W_i表示凸体的i次均值积分.当且仅当i=n-1或i=n-2时,这个问题是正确的,已被证明.作者考虑了一个对偶问题,证明了:若K与L是R~n上的星体,n-2≤i≤n-1且i∈R,则(W_i(K+L))/(W_i+1(K+L))≤(W_i(K))/(W_i+1(K))+(W_i(L))/(W_i+1(L))/(W_i+1(L))其中W_i表示星体的i次对偶均值积分.     

ON A PROBLEM OF SUMS OF MIXED POWERS （II）

ＯＮＡＰＲＯＢＬＥＭＯＦＳＵＭＳＯＦＭＩＸＥＤＰＯＷＥＲＳ（Ｉ）ＬＵＭＩＮＧＧＡＯＹＵＧＡＮＧＡｂｓｔｒａｃｔＬｅｔＲｂ，ｃ（ｎ）ｄｅｎｏｔｅｔｈｅｎｕｍｂｅｒｏｆｒｅｐｒｅｓｅｎｔａｔｉｏｎｓｏｆｎａｓｔｈｅｓｕｍｏｆｏｎｅｓｑｕａｒｅ，ｆｏ...     

关于一类中心循环的有限P-群的自同构群

确定了一类中心循环的有限p-群G的自同构群.设G=X_3(p~m)~(*n)*Z_(p~(m+r)),其中m≥1,n≥1和r≥0,并且X_3(p~m)=x,y|x~(p~m)=y~(p~m)=1,[x,y]~(p~m)=1,[x,[x,y]]=[y,[x,y]]=1.Aut_nG表示Aut G中平凡地作用在N上的元素形成的正规子群,其中G'≤N≤ζG,|N|=p~(m+s),0≤s≤r,则(i)如果p是一个奇素数,那么AutG/Aut_nG≌Z_(p~((m+s-1)(p-1))),Aut_nG/InnG≌Sp(2n,Z_(p~m))×Z_(p~(r-s)).(ii)如果p=2,那么AutG/Aut_nG≌H,其中H=1(当m+s=1时)或者Z_(2~(m+s-2))×Z_2(当m+s≥2时).进一步地,Aut_nG/InnG≌K×L,其中K=Sp(2n,Z_(2~m))(当r0时)或者O(2n,Z_(2~m))(当r=0时),L=Z_(2~(r-1))×Z_2(当m=1,s=0,r≥1时)或者Z_(2~(r-s)).     

ON CURVATURE PINCHING FOR MINIMAL AND KAEHLER SUBMANIFOLDSiWITH ISOTROPIC SECOND FUNDAMENTAL FORM

An isometrically immersed submanifold is said to have isotropic second fundamental form if the length of the second fundamental form related into any normal vector is the same one. In this note, some curvature pinching theorems for compact minimal (resp. Kaehler) submanifolds in $S^{n+p}(c)$(resp. $CP^{n+p}(c)$) with isotropic second fundamental form are given.     

Boundedness Characterization of Maximal Commutators on Orlicz Spaces in the Dunkl Setting

On the real line, the Dunkl operators$$D_{\nu}(f)(x):=\frac{d f(x)}{dx} + (2\nu+1) \frac{f(x) - f(-x)}{2x}, ~~ \quad\forall \, x \in \mathbb{R}, ~ \forall \, \nu \ge -\tfrac{1}{2}$$are differential-difference operators associated with the reflection group $\mathbb{Z}_2$ on $\mathbb{R}$, and on the $\mathbb{R}^d$ the Dunkl operators $\big\{D_{k,j}\big\}_{j=1}^{d}$ are the differential-difference operators associated with the reflection group $\mathbb{Z}_2^d$ on $\mathbb{R}^{d}$.In this paper, in the setting $\mathbb{R}$ we show that $b \in BMO(\mathbb{R},dm_{\nu})$ if and only if the maximal commutator $M_{b,\nu}$ is bounded on Orlicz spaces $L_{\Phi}(\mathbb{R},dm_{\nu})$. Also in the setting $\mathbb{R}^{d}$ we show that $b \in BMO(\mathbb{R}^{d},h_{k}^{2}(x) dx)$ if and only if the maximal commutator $M_{b,k}$ is bounded on Orlicz spaces $L_{\Phi}(\mathbb{R}^{d},h_{k}^{2}(x) dx)$.     

无$K_{1,4}$子图的图的路覆盖

For a graph G, a path cover is a set of vertex disjoint paths covering all the vertices of G, and a path cover number of G, denoted by p(G), is the minimum number of paths in a path cover among all the path covers of G. In this paper, we prove that if G is a K_(1,4)-free graph of order n and σ_(k+1)(G) ≥ n-k, then p(G) ≤ k, where σ_(k+1)(G) = min{∑v∈S d(v) : S is an independent set of G with |S| = k + 1}.     

Dynamics of a Function Related to the Primes

Let n = p1p2 ··· pk, where pi(1 ≤ i ≤ k) are primes in the descending order and are not all equal. Let Ωk(n) = P(p1 + p2)P(p2 + p3) ··· P(pk-1+ pk)P(pk+ p1), where P(n) is the largest prime factor of n. Define w0(n) = n and wi(n) = w(wi-1(n)) for all integers i ≥ 1. The smallest integer s for which there exists a positive integer t such thatΩs k(n) = Ωs+t k(n) is called the index of periodicity of n. The authors investigate the index of periodicity of n.