用系数有界限的广义多项式的L逼近

1.存在定理 在空间C[a,b]中引进L范数:即对f∈C[a,b],定义 设n是一个固定的自然数,α_j,β_i(j=1,…,n)为两组广义实数,并满足条件 α_j<+∞,β_j>-∞,α_j≤β_j,j=1,…,n.又设{g_1,…,g_n}?C[a,b]是线性无关的,记 K={p=sum from j=1 to n(a_jg_j:α_j≤a_j≤β_j,j=1,…,n}.对于f∈C[a,b],若p∈K满足     

CHARACTERIZATION THEOREM OF GENERALIZED POLYNOMIAL OF BEST APPROXIMATION HAVING BOUNDED COEFFICIENTS

Let the set of generalized polynomials having bounded coeffiicients be K={p=sum from j=1 to n α_j g_j α_j≤α_j≤β,j=1, 2,…, n}, where g_1, g_2,…, g_n are linearly independent continuous functions defined on theinterval [a,b], α_j β_j are extended real numbers satisfying α_j< ∞, β_j>-∞, andα_j≤β_j. Assumethat f is a continuous function defined on a compact set X [a, b]. This paper gives the characterizationtheorem for p being the best uniform approximation to f from K, and points out that the characteri-zation theorem can be applied in calculating the approximate solution of best approximation to f fromK.     

在Banach空间中推广的Roper-Suffridge算子(Ⅲ)

假定X是具有范数‖·‖的复Banach空间,n是一个满足dim X≥n≥2的正整数.本文考虑由下式定义的推广的Roper-Suffridge算子Φ_(n,β_22γ_2,…,β_(n+1),γ_(n+1))(f):(?)其中x∈Ω_(p1,p2,…,pn+1),β_1=1,γ_1=0和(?)这里p_j1(j=1,2,…,n+1),线性无关族{x_1,x_2,…,x_n}(?)X与{x_1~*,x_2~*,…,x_n~*}(?) X~*满足x_j~*(x_j)=‖x_j‖=1(j=1,2,…,n)和x_j~*(x_k)=0(j≠k),我们选取幂函数的单值分支满足(f(ξ)/ξ)~(β_j)|ξ=0=1和(f′(ξ))~(γ_j)|ξ=0=1,j=2,…,n+1.本文将证明:对某些合适的常数β_j,γ_j,算子Φ_(n,β_2,γ_2,…,β_(n+1),γ_(n+1))(f)在Ω_(p_1,p_2,…,p_(n+1))上保持α阶的殆β型螺形映照和α阶的β型螺形映照.     

广义周期样条类的极值问题和广义Bernoulli核的宽度

本文研究由实系数线性系微分算子 P_r(D)=(D~2-2α_8D α_8~2 β_8~2)(D-λ_i)(α_8、β_8、λ∈R,β_8>0)定义的2π周期函数类={f:f~((r-1))绝对连续.f_(j)(0)=f~(j)(2π),j=0,1…,r-1,P_r(D)f(t)dt=0}当 p=1,2,∞,n>N(N 为某一确定的自然数)或0≤<1/4,1≤p≤∞,n=1,2,3,…时,我们求得了 d_n(,L)、d′_2n(,L)、d~2n(,L)d_2n(,L_p)、d′_2n(,L_p)、d_n(,L_p)等宽度的精确估计.我们还讨论了用广义周期样条的最佳逼近,从而找到了相当广泛的一类广义周期样条做为 d_2n(,L)的极子空间.     

The generalized Roper-Suffridge extension operator on bounded complete Reinhardt domains

The generalized Roper-Suffridge extension operator Ф(f) on the bounded complete Reinhardt domain Ω in Cn with n ≥ 2 is defined by Φrn,β2,γ2,…,βn,γn(f)(z)=(rf(z1/r),(rf(z1/r)/z1)β2(f'(z1/r))γ2z2,…,(rf(z1/r)/z1)βn(f'(z1/r)γnzn) for (z1,z2,…,zn) ∈Ω, where r = r(Ω) = sup{|z1| (z1,z2,…,zn) ∈ Ω},0 ≤ γj ≤ 1 -βj,0 ≤ βj ≤ 1,and we choose the branch of the power functions such that (f(z1)/z1)βj |z1=0 = 1 and (f′(z1))γj |z1=0 =1,j = 2,…,n. In this paper, we prove that the operator Фrn,β2,γ2,…,βn,γn(f) is from the subset of S*α(U) to S*α(Ω)(0 ≤ α ＜ 1) on Ω and the operator Фrn,β2,γ2,…, βn,γn(f) preserves the starlikeness of order α or the spirallikeness of type β on Dp for some suitable constantsβj,γj,pj, where Dp ={(z1,z2,…,zn) ∈ Cn ∑nj=1|zj|pj ＜ 1} (pj ＞ 0, j = 1,2,…,n), U is the unit disc in the complex plane C, and Sα* (Ω) is the class of all normalized starlike mappings of order α on Ω. We also obtain that Φrn,β2,γ2,…,γn(f) ∈ S*α(Dp) if and only if f ∈ S*a(U) for 0 ≤ α ＜ 1 and some suitable constants βj,γj,pj.     

参数曲线所围图形的面积

众所周知,直角坐标曲线y=f(x)与直线x=a,x=b及x轴所围曲边梯形的面积A=integral from n=a to b(f(x)dx),其中a≤b,f(x)在[a,b]上连续,f(x)≥0;极坐标曲线γ=γ(θ)与射线θ=a,θ=β所围扇形的面积A=(1/2)integral from n=αto β(γ~2(θ)dθ),其中α≤β,γ(θ)在[α,β]上连续.     

SOLUTIONS TO A SECOND-ORDER MULTI-POINT BOUNDARY VALUE PROBLEM AT RESONANCE

This article deals with the following second-order multi-point boundary value problem x′′(t) = f(t,x(t),x′(t))+e(t),t ∈(0,1),x′(0)=(α_ix′(ξ_i) from i=1 to m,x(1)=(β_jx(ηj) from j=1 to n .Under the resonance conditions α_i from i=1 to m =1,β_j from j=1 to n=1,β_jηj from j=1 to n =1,by applying the coincidence degree theory,some existence results of the problem are established.The emphasis here is that the dimension of the linear operator is two.In this paper,we extend and improve some previously known results like the ones in the references.     

一类非线性广义样条最佳L_p逼近的光滑性

设L是常系数n阶线性微分算子,m∈N, 0=s_00适当小,v=1,…,r}本文证明了设f∈L_p[0,1],1≤p<∞,那末当n≥2时,存在f的最佳L_p[0,1]逼近样条(?)∈C[0,1]∩φ~*(m,q)。当n≥3时,存在f的最佳L_p[0,1]逼近样条(?)∈C~1[0,1]∩φ~*(m,q)。     

分段线性规划算法的一个注记

求解分段线性规划问题inf S(x) s.t.Ax≤b 0≤x≤(?) (1)其中(?)=((?)_1,(?)_2,…,(?)_n)及 b=(b_1,b_2,…,b_m)~T 是已知向量,A 是已知的(m,n)矩阵,元素为 α_(ij)。目标函数 s(x)是分段线性函数。即对[0,(?)_j)(j=1,2,…,n)存在分划0=x_j~(0)相似文献   

Weighted Integral Means of Mixed Areas and Lengths Under Holomorphic Mappings

This note addresses monotonic growths and logarithmic convexities of the weighted((1-t2)αdt2,-∞α∞,0t1)integral means Aα,β(f,)and Lα,β(f,)of the mixed area(πr2)-βA(f,r)and the mixed length(2πr)-βL(f,r)(0≤β≤1 and0r1)of f(rD)and f(rD)under a holomorphic map f from the unit disk D into the finite complex plane C.     

Boundedness of generalized higher commutators of Marcinkiewicz integrals

Let (b) ＝ (b1,…,bm) be a finite family of locally integrable functions. Then,we introduce generalized higher commutator of Marcinkiwicz integral as follows:μ(b)Ω=(∫∞o|F(b)Ω,t(f)(x)|2et/t)1/2,whereF(b)Ω(f)(x)＝1/t∫|x-y|≤tΩ(x-y)/|x-y|n-1m∏j=1(bj(x)-bj(y))f(y)dy.When bj ∈(A)βj, 1≤j≤m, 0＜βj＜1,m∑j=1βj =β＜n, and Ω is homogeneous of degree zero and satisfies the cancelation condition, we prove that μ(b)Ω is bounded from Lp(Rn)to Ls(Rn), where 1 ＜ p ＜ n/β and 1/s = 1/p -β/n. Moreover, if Ω also satisfies some Lq-Dini condition, then μ(b)Ω is bounded from Lp(Rn) to (F)β,∞p(Rn) and on certain Hardy spaces. The article extends some known results.     

一个改进的超记忆梯度法的收敛性及其敛速估计

一、算法 问题:min{f(x)|x∈E~n},f(x)为实值函数; 记号:gj为f(x)在x_j处的梯度列向量,x_*为问题的最优解,H(x)、H_*分别表示f(x)在x和x_*处的Hessian矩阵,上标“,”表示矩阵的转置。 给定实数序列{β_j}、β_j≥0、β_j→0(j→∞),常数a>0,整数k_1相似文献   

有界完全Reinhardt域上推广的Roper-Suffridge算子

在$\C^n$中的有界完全Reinhardt域$\Omega$上推广的Roper-Suffridge算子$\Phi(f)$定义为 \begin{eqnarray*} \Phi^r_{n,\beta_2, \gamma_2,\ldots, \beta_n, \gamma_n}(f)(z)\!=\!\Big(rf\Big(\frac{z_1}{r}\Big), \Big(\frac{rf(\frac{z_1}{r})}{z_1}\Big)^{\beta_2}\Big(f’\Big(\frac{z_1}{r}\Big)\Big)^{\gamma_2}z_2,\ldots, \Big(\frac{rf(\frac{z_1}{r})}{z_1}\Big)^{\beta_n}\Big(f’\Big(\frac{z_1}{r}\Big)\Big)^{\gamma_n}z_n \Big), \end{eqnarray*} 其中 $n\geq2$, $(z_1, z_2,\ldots, z_n)\in \Omega$, $r=r(\Omega)=\sup\{|z_1|: (z_1, z_2,\ldots, z_n)\in \Omega\}, 0\leq \gamma_j\leq 1-\beta_j, 0\leq \beta_j\leq 1$, 这里选取幂函数的单值解析分支, 使得 $(\frac{f(z_1)}{z_1})^{\beta_j}|_{z_1=0}= 1$ 和 $(f’(z_1))^{\gamma_j}|_{z_1=0}=1, j=2,\ldots, n$. 证明了 $\Omega$上的算子 $\Phi^r_{n,\beta_2, \gamma_2,\ldots, \beta_n, \gamma_n}(f)$ 是将 $S^*_\alpha(U)$ 的子集映入$S^*_\alpha\,(\Omega)\,(0\leq \alpha<1)$, 且对于一些合适的常数 $\beta_j, \gamma_j, p_j$, $D_p$上的这个算子 $\Phi^r_{n,\beta_2, \gamma_2,\ldots, \beta_n, \gamma_n}(f)$ 保持$\alpha$阶星形性或保持$\beta$ 型螺形性, 其中 $ D_p=\bigg\{(z_1, z_2,\ldots, z_n)\in \C^n: \he{j=1}{n}|z_j|^{p_j}<1\bigg\},\quad p_j>0, j=1, 2,\ldots, n, $ $U$是复平面$\C$上的单位圆, $S^*_\alpha(\Omega)$ 是 $\Omega$ 上所有正规化$\alpha$阶星形映射所成的类. 也得到: 对于某些合适的常数 $\beta_j, \gamma_j, p_j$ 和 在$\C^n$中的有界完全Reinhardt域$\Omega$上推广的Roper-Suffridge算子$\Phi(f)$定义为 \begin{eqnarray*} \Phi^r_{n,\beta_2, \gamma_2,\ldots, \beta_n, \gamma_n}(f)(z)\!=\!\Big(rf\Big(\frac{z_1}{r}\Big), \Big(\frac{rf(\frac{z_1}{r})}{z_1}\Big)^{\beta_2}\Big(f’\Big(\frac{z_1}{r}\Big)\Big)^{\gamma_2}z_2,\ldots, \Big(\frac{rf(\frac{z_1}{r})}{z_1}\Big)^{\beta_n}\Big(f’\Big(\frac{z_1}{r}\Big)\Big)^{\gamma_n}z_n \Big), \end{eqnarray*} 其中 $n\geq2$, $(z_1, z_2,\ldots, z_n)\in \Omega$, $r=r(\Omega)=\sup\{|z_1|: (z_1, z_2,\ldots, z_n)\in \Omega\}, 0\leq \gamma_j\leq 1-\beta_j, 0\leq \beta_j\leq 1$, 这里选取幂函数的单值解析分支, 使得 $(\frac{f(z_1)}{z_1})^{\beta_j}|_{z_1=0}= 1$ 和 $(f’(z_1))^{\gamma_j}|_{z_1=0}=1, j=2,\ldots, n$. 证明了 $\Omega$上的算子 $\Phi^r_{n,\beta_2, \gamma_2,\ldots, \beta_n, \gamma_n}(f)$ 是将 $S^*_\alpha(U)$ 的子集映入$S^*_\alpha\,(\Omega)\,(0\leq \alpha<1)$, 且对于一些合适的常数 $\beta_j, \gamma_j, p_j$, $D_p$上的这个算子 $\Phi^r_{n,\beta_2, \gamma_2,\ldots, \beta_n, \gamma_n}(f)$ 保持$\alpha$阶星形性或保持$\beta$ 型螺形性, 其中 $ D_p=\bigg\{(z_1, z_2,\ldots, z_n)\in \C^n: \he{j=1}{n}|z_j|^{p_j}<1\bigg\},\quad p_j>0, j=1, 2,\ldots, n, $ $U$是复平面$\C$上的单位圆, $S^*_\alpha(\Omega)$ 是 $\Omega$ 上所有正规化$\alpha$阶星形映射所成的类. 也得到: 对于某些合适的常数 $\beta_j, \gamma_j, p_j$ 和 在C~n中的有界完全Reinhardt域Ω上推广的Roper-Suffridge算子Φ(f)定义为Φ_(n,β_2,γ_2,…,β_n,γ_n)~r(f)(z)=(rf(z_1/r),((rf(z_1/r))/z_1)~(β_2)(f′(z_1/r))~γ_2_(z_2,…,)((rf(z_1/r))/z_1)~(β_n)(f′(z_1/r))~(γ_n)_(z_n),其中n≥2,(z_1,z_2,…,z_n)∈Ω,r=r(Ω)=sup{|z_1|:(z_1,z_2,…,z_n)∈Ω},0≤γ_j≤1-β_j,0≤β_j≤1,这里选取幂函数的单值解析分支,使得((f(z_1))/z_1)~(β_j)|_(z_1=0)=1和(f′(z_1))~(γ_j)|_(z_1=0)=1,j= 2,…,n.证明了Ω上的算子Φ_(n,β_2,γ_2,…,β_n,γ_n)~r(f)是将S_α~*(U)的子集映入S_α~*(Ω)(0≤α<1),且对于一些合适的常数β_j,γ_j,p_j,D_p上的这个算子Φ_(n,β_2,γ_2,…,β_n,γ_n)~r(f)保持α阶星形性或保持β型螺形性,其中(?) U是复平面C上的单位圆,S_α~*(Ω)是Ω上所有正规化α阶星形映射所成的类.也得到:对于某些合适的常数β_j,γ_j,p_j和0≤α<1,Φ_(n,β_2,γ_2,…,β_n,γ_n)~r(f)∈S_α~*(D_p)当且仅当f∈S_α~*(U).     

多线性分数次积分算子交换子的有界性

Ibαf ( x) =∫R ∏mj=1( bj( x) - bj( y) ) 1| x - y| n-αf ( y) dyare considered.The following priori estimates are proved.For 1 01Φ1t| {y∈Rn:| Ibαf( y) | >t}| 1q ≤csupt>01Φ1t| {y∈Rn:ML( log L) 1r ,α(‖b‖f ) ( y) >t}| 1q,where‖b‖=∏mj=1‖bj‖Oscexp Lrj,Φ( t) =t( 1 + log+t) 1r,1r =1r1+ ...+ 1rm,ML(…     

I.J.Matrix定理的进一步推广

文献 [1]— [5 ]连续讨论了 I.J.Matrix定理的一些推广及应用 ,特别是文 [5 ]利用高阶微分的知识简明地给出了一个推广 ,本文给出其进一步的推广 .设 a0 ,a1 ,… ,an 是 n 1个互不相同且不为零的数 ,f ( x)是次数为 m的多项式 ,文 [5 ]讨论的是m相似文献   

关于Walsh系逼近恒同核

考虑一类Walsh系逼近恒同核其中a_(j,i)为某些参数,依赖于n,r或仅依赖于n,并且φ_j为Rademacher函数,j=0,1,…,n-l;l=1,…,p-1,0≤r<1。在一定条件下,例如,可得强逼近过程或C[0,1)。此外有其中A和B为常数。 文中还给出WW型正核定义并建立一个Korovkin型定理。     

一类具有多个偏差变元的二阶中立型泛函微分方程的周期解

利用重合度理论,获得了一类具有多个偏差变元的二阶中立型泛函微分方程(d~2)/(dt~2)(u(t)-(sum from j=1 to n)c_ju(t-r_j))=f(u(t))u′(t)+α(t)g(u(t))+(sum from j=1 to n)β_j(t)g(u(t-γ_j(t)))+p(t)周期解存在性的新的充分条件,改进了已有文献的相关结果.     

用Fourier部分和子序列的线性平均逼近周期函数

1.主要结果为其Fourier级数。以Sn(f,x)表示它的第n部分和,以(f, x)表示α阶Cesaro平均,也即其中(α)_i=Γ(α+j+1)/Γ(α+1)Γ(j+1)。对于空间X=C_(2x)或是L_(2π)以E_v(f)_x表示在X中借助不超过v阶的三角多项式逼近f(x)的最佳逼近。根据С. Б. Стечкин和孙永生的结果知道,若α>0而x=C_(2x),则对于一切f(x)X成立着下述不等式     

STRONG UNIQUENESS OF GENERALIZED P0LYNOMIAL OF BEST APPROXIMATION HAVING BOUNDED COEFFICIENTS

Let the set of generalized polynomials haviug bounded coefficients bewhere g_1, g_2,…, g_n are linearly independent continuous functions defined on the interval [a, b], α_jβ_j, are extended real numbers satisfying α_j< ∞, β_j>-∞ and α_j≤β_j.Assume that f is a continuousfunction defined on a compact set X[a, b]. In the paper, we first give the sufficient conditions forthe polynomial of best uniform approxmation to f from K being unique and strongly unique.Furthermore, we give two forms of necessary and sufficient conditions for the best approximationto be strongly unique.     

五次缺插值样条的渐近性态

f(x)定义于[0,1]。将[0,1]n等分,记x_j=jh,j=0,…,n.h=1/n,且 f~(α)(x_j)=f_j~(α),j=0,…,n;α=0,1,…,5。 A.Meir和A.Sharma提出五次缺插值样条函数,即满足下面条件的函数s_n(x): (i)s_n(x)∈C~3[0,1], (ii)在区间[x_j,x_(j 1)]上(j=0,…,n-1),s_n(x)是五次多项式, (iii)s_n(x_j)=f_j,s″_n(x_j)=f″_j,j=0,…,n, (iv)s′_n(0)=f′_0,s′_n(1)=f′_n。 (1) [1]还考虑了把(1)中的(iv)换成 (iv′)s′′′_n(0)=f′′′_0,s′′′_n(1)=f′′′_n (2)的五次样条。为叙述方便,我们分别称之为(Ⅰ)型、(Ⅱ)型缺插值样条。[1]证明了(Ⅰ),(Ⅱ)型插值样条在n为奇数时是唯一存在的。[2,3,4]继续了这方面的工作,得到了一