半线性蜕缩椭圆型方程的Dirichlet问题

设Ω(?)R~n(n≥2)是光滑有界区域.讨论如下的半线性蜕缩椭圆型方程的Dirichlet问题Lu ≡-sum from i,j=1 to n((?)/(?)x_i)(aij(x)((?)u/(?)xj)=g(x,u) (x,u),在Ω中,u=0,在(?)Ω上。(1)这里,且sum from i,j=1 to n(aijξiξj≥k sum from i=1 to n(ρ~a_i(x)ξ_i~2),(?)x∈(?),(?)ξ∈R~n,(2)     

The Berry-Esseen Theorem and Non-Uniform Estimate for U-Statistics

Let X_1,X_2,…,X_n be independent random variables. Define a U-statistic by U_n(?)~(-1)sum from 1≤i≤j≤n (h(X_i,X_j), where h(x,y) is a symmetric function of two variables x,y and that Eh(X_i,X_j)=0(i≠j, i,j=1,2,…,n). Write g_j(X_i)=E(h(x_i,x_j)|x_i),g(X_1)=1/n-1 sum from j=1 j≠i to n g_j(X_i) We give the following two theorem: Theorem 1 Suppore that     

关于Littlewood的一个问题

本文证明了: (1)如果{a_n}_n~N=1是非负不减序列,p>0,q>0,0≤r≤1,且p(q+r)≥q+p,则sum from n=1 to N(a_n~pA_n~q)(sum from m=n to N(a_n~(1+p/q)~r≤1·sum from n=1 to N(a_n~pA_n~q)~(1+p/q),其中A_n=sum from m=n to n (a_m).上述不等式在0≤r≤1时完全解决了H.Alzer~([4])在1996年提出的一个问题,且1是最佳常数; (2)如果{a_n}_n~N=1是非负序列,p,p≥1,r>0,r(p-1)≤2(q-1),令α=((p-1)(q+r)+p~2+1)/(p+1) β=(2p+2r+p-1)/(q+1),σ=(q+r-1)/(p+q+r)则sum from n=1 to N (a_n~p)sum from i=1 to n (a_i~qA_i~r)≤2~σsum from n=1 to N(a_n~αA_n~β)(0.2)(0.2)式改进了G.Be(?)et~([2,3])在1987年对Littlewood一个问题的结果,常数因子的3/2降为2~(3/2)=1.2598…     

布尼雅可夫斯基不等式的推广

定理:不等式 (sum from i=1 to m(a_(1i) a_(2i)…a_(ni)))~n≤≤sum from i=1 to m(a_(1i))~n sum from i=1 to m(a_(2i))~n…sum from i=1 to m(a_(ni))~n對於任意自然數n都成立,其中a_(ki)為正數(K=1,2,…,n,i=1,2,…,m). 證明: 設 A_K~n=sum from i=1 to m(a_(Ki))~n (K=1,2,…,n), x_(Ki)=a_(Ki)/A_K,(K=1,2,…,n i=1,2,…,m)則從n侗正數的幾何平均值小於或等於其算術平均值這個結果可得 x_(1i)x_(2i)…x_(ni)≤((x_(1i))~n+(x_(2i))~n+…+(x_(ni))~n)/n由此更推得a_(1i)a_(2i)…a_(ni)=A_1A_2…A_n(x_(1i)x_(2i)…x_(ni)≤     

拟线性方程组的时滞问题

§1.引理和定理1.在动力气象学中常用到可压缩流体力学的一组闭合方程组:(?)u_j/(?)t sum from i=1 to 3 u_i(?)u_j/(?)x_i α (?)P/(?)x_j ξ_(2j)fu_1 ξ_(3j)fu_2=f_j(t,x),j=1,2,3,(1.1)(?)_α/(?)t sum from i=1 to 3 u_i(?)α/(?)x_i=αsum from i=1 to 3 (?)u_i/(?)x_i,(1.2)Pα=RT,(1.3)C_P{(?)T/(?)t sum from i=1 to 3 u_i(?)T/(?)x_i}-α{(?)P/(?)t sum from i=1 to 3 u_i (?)P/(?)x_i}=0 (1.4)其中(?)x=(x_1,x_2,x_3),u_1,u_2,u_3,是风速的分量,α是比容,P 是压力,T 是绝对温度,柯氏参数 f=f(x_1,x_2)都是已知函数.R,C_p 为正常数.由于α(?)0,从(1.2)-(1.4)式消去 T,记     

A NECESSARY AND SUFFICIENT CONDITION FOR THE OSCILLATION OF HIGHER-ORDER NEUTRAL EQUATIONS WITH SEVERAL DELAYS

Consider the higher-order neutral delay differential equationd~t/dt~n(x(t)+sum from i=1 to lp_ix(t-τ_i)-sum from j=1 to mr_jx(t-ρ_j))+sum from k=1 to Nq_kx(t-u_k)=0,(A)where the coefficients and the delays are nonnegative constants with n≥2 even. Then anecessary and sufficient condition for the oscillation of (A) is that the characteristicequationλ~n+λ~nsum from i=1 to lp_ie~(-λτ_i-λ~n)sum from j=1 to mr_je~(-λρ_j)+sum from k=1 to Nq_ke~(-λρ_k)=0has no real roots.     

一类指数函数的高阶导数

在微积分学中,指数函数f(x)=e~(-x)~(-2)(x≠0)是一个非常简单而十分重要的初等偶函数,尤其是在函数的幂级数展开中,需要研究这个指数函数的有限形式的高阶导数及其性质.本文对此问题进行了研究,并得到如下结果:设f(x)=e~(-x)~(-2)(x≠0)的n阶导数为f_n(x)=fn(x)e~(-x)~(-2),则f_n(x)=sum from i=1 to n(-1)~(n+i)C_i(n)x~(-n-2i),其中C_1(n)=(n+1)!,C_i(n)=2sum from j=i to n(n+2i-1)!/(j+2i-1)!C_(i-1)(j-1),(1i≤n).     

非负全连续算子的谱模

设 A=(a_(ij))是 l_2中一个全连续算子,其中a_(i_1j)≥0.当 A~*A 为不可约时,本文证明了|||A|||+2=min{r(B)c_1(C)∶A=BoC},其中 A=BoC 表示对一切 i,j,a_(ij)=b_(ji)c_(ji),r(B)=sup(sum from j=1 to ∞ |b_(ij)|~2)~(1/2),c_1(C)=(sum from i=1 to ∞ (c_(ji)~2)~(1/2),并给出极小解的具体形式.文中所有结果均适用于 A_(mn)为一 m×n 矩阵的情形     

一个代数不等式的加强

近两年,在众多刊物上,载有不等式: multiply from i=1 to n(x_i+1/x_i)≥(λ/n+n/λ) (*)这里x_i∈R~+(i=1,2,…,n),x_1+x_2+…+x_n=λ≤n,仅当x_1=x_2=…=x_n时(*)式取等号。现在,我们给出(*)的一个加强: 定理设x_i∈R~+(i=1,2,…,n,n≥2),且sum from i=1 to n x_i=λ(常数)≤n,则 sum from i=1 to n(x_i+1/x_i)~(-1)≤n(λ/n+n/λ)~(-1) (1)当且仅当x_1=x_2+…=x_n时,(1)式中的等号成立。     

一个关于非负矩阵的不等式

证明:若(xij)是一个元素不全为零的m×n非负矩阵,则当0相似文献   

常系数非齐线性递推式的解的显式表示

本文给出常系数非齐线性递推式(?)的解的显式表达式 H(m)=sum from i=0 to k-1(sum from j=i to k-1 b_ja_(k-j+i))D_(m-k-i)+sum from i=0 to m-k D_if(m-i)(m≥k)其中D_m=sum x_1+2x_2+…+kx_k=m x_j≥0(i=1,2,…,k)(?)a_1~x1a_2~x2…a_k~xk.     

关于凸函数的Hadamard不等式的拓广(英文)

设,是区间[a,b]上连续的凸函数。我们证明了Hadamard的不等式 f(a+b/2)≤1/b-a integral from a to b (f(x)dx)≤f(a)+f(b)/2可以拓广成对[a,b]中任意n+1个点x_0,…,x_n和正数组p_0,…,p_n都成立的下列不等式 f(sum from i=0 to n (p_ix_i)/sum from i=0 to n (p_i))≤|Ω|~(-1) integral from Ω (f(x(t))dt)≤sum from i=0 to n (p_if(x_i)/sum from i=0 to n (p_i),式中Ω是一个包含于n维单位立方体的n维长方体,其重心的第i个坐标为sum from i=i to n (p_i)/sum from i=i-1 (p_i),|Ω|为Ω的体积,对Ω中的任意点t=(t_1,…,t_n) ω(t)=x_0(1-t_1)+sum from i=1 to n-1 (x_i(1-t_(i+1))) multiply from i=1 to i (t_i+x_n) multiply from i=1 to n (t_i)。不等式中两个等号分别成立的情形亦已被分离出来。 此不等式是著名的Jensen不等式的精密化。     

条件L泛函的核估计及其Bootstrap逼近

设(X,y)为取值于 R~d×R~1的随机变量,X 具有边缘分布 F(x),Y 关于 X 的条件分布为 F(y|x).对于条件 L 泛函θ_1(x)=integral from n=0 to 1 J(y)F~(-1)(y|x)dy(1)θ(x)=integral from n=0 to 1 J(y)F~(-1)(y|x)dy+sum from j=1 to k a_jF~(-1)(p_j|x)(2)在[1]中曾给出了它们的近邻估计,并讨论了估计的渐近性质(其中 F~(-1)(x)=inf{t:F(t)≥x}).在本文中,我们将用核函数方法构造它们的另一类估计,并讨论估计的一些渐近性质.设(X_1,Y_1),(X_2,Y_2),…是(X,Y)的一个样本列,取 w_n_i(x)=K((x-X_i)/h_n)/sum from i=1 to n K((x-X_i)/h_n),其中 K 为 R~d 上的概率密度函数,并有0相似文献   

链积中参数对称的反链

设k-i为正整数,i=1,2,…,n,直积S=Ⅰ_(R_1)×Ⅰ_(R_2)×…×Ⅰ_(k_n)={x_1,x_2,…,x_n,0≤x_i≤k_i}叫做链积,对任意的在偏序“<”下为有限偏序集。r(x)=sum from i(x_i)原S的秩函数,叫做S的Whitney数记k=sum from i=1 to n(k_i,k_1=k_2=k_n=1)时,S即为布尔代数B_n。 设为S中的反链,{P_i,i=0,1,…,n}叫做反链的参数,若成立     

Primitive Roots and Linearized Polynomials

Let f(x) = sum from t=0 to n α_ix~i∈GF(p)[x],we associate it with a ploynomial f~*(x)=sum from i=0 to n α_ix~(p~i),f(x) and f~*(x)are called p-associates of each other. f~*(x) is called a p-ploynomial,customary to speak of linearized polynomial. Let f(x)=x~m- 1/g(x), m = m_1~r, q = p~m, g(x)∈GF(p)[x],r be the order of g(x). Cohen and the author observed that if m_1≥2, there alwaysexsists a primitive roots ζ∈GF(q) suck that f~*(ζ) = f~*(c), here f~*(c)≠0. In fact     

OSCILLATIONS OF NEUTRAL DIFFERENTIAL DIFFERENCE EQUATIONS

Recently the authors have studied the oscillations of some neutral differential difference equations and obtained very good results (see [1—4]). In this paper we consider the oscillations of the neutral differential difference equationd/dt[x(t)+sum from i=1 px(t-τ)+sum form j=1 to n qx(t-σ)=0, t≥t,] (*)where p, τ, q and σ (i=1, 2, …, m; j=1, 2, …, n) are positive constants. Some sufficient conditions for all solutions of (*) to oscillate are obtained. And in some ease we give neeessaxy and sufficient conditions for (*) to oscillate.     

退缩椭圆型方程的边值问题

<正> 在 R~n 的有界凸区域Ω上考虑椭圆型方程Lu≡sum from i,j=1 to n (a_(ij)(x)u_(xi)_(xj)+sum from i=1 to n b_i(x)u_i+c(x)u=f(x),(1)设对 x∈(?)及所有的实数组(ξ_1,ξ_2,…,ξ_n)sum from i,j=1 to n a_(ij)(x)ξ_iξ_j≥λ(x)sum from i=1 to n ξ_i~2≥0,a_(ji)(x)∈C(?),即算子 L(u)可能退缩而为退缩椭圆型算子。记(?)的边界为∑,∑上满足 sum from ij=1 to n a_(ij)n_in_j=0的点集为∑_0,(n_1,…,n_n)表示∑上的内单位法向量,∑_3=∑\∑_0,设其 n-1维测度非零,则对方程(1)可提如下的边值问题:     

常系数线性齐次递归式的一般解公式

本文给出常系数线性递归式 a_n=α_1a_(n-1)+α_2a_(n-2)+…+α_pa_(n-p),a_0=c_0,a_1=c_1,…,a_(p-1)=c_(p-1)的一般解公式 a_n=sum from k=0 to p-1(sum from i=k to p-1 c_iα_(p-i+k))F_(n-p-k)(n≥p),其中(?)     

复旦大学1984年硕士研究生入学考试试题

1.设x_0,x_1,…,x_n,x是n+2个相异点,证明 f(x_0,x_1,…,x_n,x)=sum from i=0 to n(f(x_j,x)/(multiply from (?) to n(x_j-x_1))) 其中f(xj,x)和f(x_o,x_1,…,x_n,x)分别表示函数f(x)的一阶和n+1阶差商。 2.设n阶线性方程组Ax=b中n×n矩阵A的顺序主子式det(A1)≠0(i=1,…n),令(n+1)×(n+1)矩阵B为     

具多滞量和正负系数中立型微分方程解的渐近性质

该文考虑多滞量和正负系数中立型方程[x(t)-sum from n=1 to l(1/n)C_A(t)x(t-r_n)] sum from i=1 to (1/i)P_i(t)x()t-τ_i)-sum from j=1 to n(1/j)Q_j(t)x(t-σ_j)=0,其中C_A(k=1,…,l),P_i(i=1,…,m),Q_j(j=1…,n)∈C([to,∞co),R~ ),0≤τ_l<…<τ_m,0≤σ_1<…<σ_n,0相似文献