Heisenberg群上一类左不变LPDO的局部基本解及局部可解性

In this paper it is proved that local fundamental solution exists in some space W^m(H_n) (m∈Z), if the left invariant differential operator on the Heisenberg group H_n satisfies certain condition. The main results are:l.Let L be a left invariant differential operator on H_n. If there exist R≥0, r,s∈R and operators {B_λ|λ∈Γ_R} ∈V^s(Γ_R, M^r) such that, for almost all λ∈Γ_R, B_λ is the right inverse of Ⅱ_λ(L), then there exists E∈W^m(H_n) (when m≥0 or m even) or E∈W^m-1(H_n) (when m<0 and odd) such that LE =δ(near the origie) Where m=min([r],-[2s]-n-2); 2. Let L(W,T) be of the form (3.1). If there exist R≥0 and r,s∈R such that when |λ|≥R,(?) and C_λ≥ C|λ|^x(C>0), then the same conclusion as above holds with m=min(-[2r]-n-2,[-2s]-n-2).     

关于反向适应序列的一些结果

Let X be a Banach space, (x_n, F_n, n<- 1) a X-valued adapted sequence on probability space (Q, F, P) . Let T be all stopping times with respect to(F_n,n < - 1) . (x_n, F_n,n< - 1) is called a T- uniform amart if there exists a t₀∈T such that for each t∈T with t0,E‖x_t‖<∞ and if (?)=0.In this paper we prove that.     

GCD和GCUD矩阵行列式的一个不等式（英）

Let S = {x₁, x₂,..., x_n} be a set of distinct positive integers. The n x n matrix (S) whose i, j-entry is the greatest common divisor (x_i, x_j) of x_i and x_j is called the GCD matrix on S. A divisor d of x is said to be a unitary divisor of x if (d, x/d) = 1. The greatest common unitary divisor (GCUD) matrix (S^**) is defined analogously. We show that if S is both GCD-closed and GCUD-closed, then det(S^**) ≥ det(S), where the equality holds if and Only if (S^**) = (S).     

关于n维单形的一个不等式

Let x₁,x₂… ,x_n are vectors set out from any vertex of n-simplex. The ineluded angle of x_i and x_j is a_ij , and G=(?)a_ij, the volume of this simplex is V. In this paper, we prove the inequality as below:(?) When n=2, the equality holds in (*) , when n≥3, the equality holds in (*) if {x_i} is orthogonal set.     

关于Von Mises统计量Berry-Esseen定理的一点注记

Let V_n be a von Mises Statistice with kernel φ(x₁,x₂,… ,x_m).     

非参数回归函数最近邻估计Lp收敛的速度

Let (X,Y) be a R^d×R¹-valued random vector with E(|Y|)<∞,m(x)=E(Y|X=x) be the regression funvion of Y with respect to X.Suppose that (X_i, Y_i),i=1, …,n, are iid samples drawn from (X,Y). It is desired to estimate m(x) based on these samples,everoye discussed in 1981 (see [2]) the pointwise L_p-convergence of the nearest neigthoor estimate m_n(x) (see (5) of the present paper). In this article we further study the rate of this convergence.It is shown that if there exists p≥2 such that E |Y|^p<∞,then E|m_n(x)-m(x)|^p=O(n^-p/(d+2))a.s. for suitabte choice of the weighte C_m (see(4) of the present paper).     

线性模型中误差方差估计的指数收敛速度

Suppose given a linear model y_j=x'_jβ+μ_j, j=1,2,…, The random errors all have a mean zero and unknown variance σ², 0<σ²<∞. Let σ_n² be the estimate of σ² based on the residual sum of squares and calculated from (x_j, y_j), j=1,…,n. In this paper we show that if μ₁,μ₂,…, are independent but not necessarily identically distributed, and some further conditions on {μ_j} and (x₁|…|x_n) are satisfied, then for any ε>0 there exist constant ρ_ε, 0<ρ_ε<1, Such that P(|σ_n²-σ²|≥ε)=O(ρ_εⁿ).     

Padé算子连续的条件

Let r_{m, n}=P_{m, n}/ Q_{m, n} be the Padé approximation of order (m, n) for a given power series f: Q_{m, n}f- P_{m, n}= O(z^m+n+1+j), j is as large as possible, m′ ,n′ are the exact degree of p_{m, n} and Q_{m, n} respectively and d = min{m-m′ ,n-n′}. Let T_{m, n} be the operator that maps f on r_{m, n} . Then T_{m, n} is continuous if and only if d + (j-|j|)/2= 0. This condition is equal to that r_{m, n} is on the border of a Padé block.The results obtained by H. Werner and L.Wuytack have been modified and cor reeled in this paper.     

质环的求导和交换性

In this paper, we generalize some corresponding results of [1-4]. We obtain the main results as the following:Theorem 1 Let R be a prime ring of characteristic not 2 with nontrivial derivations d₁,d₂ and let U be a nonzero ideal of R . If C is the center of R, then the following conditions are equivalent : (i)d₁,d₂(x)∈C for all x∈U; (ii) [d₁(x),d₂(y)]∈C for all x,y∈U; (iii) d₁(x)d₂(y)+d₂(x)d₁(y)∈C for all x,y∈U; (iv) R is commutative.Theorem 2 Let R be a prime ring with nontrivial derivations d₁,d₂,…, d_n and U be a nonzero ideal of R. Let C be the center of R. If d₁(x₁)d₂(x₂)…d_n(x_n)∈C for all x₁, x₂…x_n)∈U, then R is commutative.     

关于线性模型中误差方差估计中心极限定理余项的非一致性估计

in linear models, the error varianceσ2 of random errors is usually estimat-ted by the residual sum of squares (divided by a su ita ble degree of free-dom), based on the first n observation, (denote it by σ_n²). it is well known t that under certain conditions, the distribution of this estimate, when standardised, converges to the standard normal distribution. In this paper, it is shown that |G_n(x)-Ф(x)|=O(n^-δ/2(1+|x|)^-(2+δ)). when the errors are indepedent (maynot be identically distributed) and their 4 + 2δ order moments exist, where G_n(x) is the distribution of (σ_n²-σ²/(varσ_n²)^1/2,Ф(x)=1/(2π)^1/2∫_-∞^xe^-r2/2dt.