随机中止试验的线性模型中参数估计的几个性质

When sample size is a sequence of r.v., the parametric estimates in linear models are interesting both theoretically and practically. For linear models Y_i=x_iβ+e_i,i=1,2,…where {e_i} are p-dimensional i .i .d.r.v′.s with Ee₁=0. Var e₁=σ²,0<σ²<∞. we consider estimate σ²(v_n) of error variance σ² and least squares estimate β(v_n) of regression coefficient β, here {v_n} is a sequence of r.v. with positve integers larger than P. In this paper some properties of estimates are discussed . Those are unbiasedness, consistency and normality . For σ²(v_n), we also obtain some orders for convergence to normal distribution.     

Stability of Rotation Relations of Three Unitaries with the Flip Action in C*-Algebras*

The authors show that if Θ = (θ_jk) is a 3 × 3 totally irrational real skewsymmetric matrix, where θ_jk ∈ [0, 1) for j, k = 1, 2, 3, then for any ε > 0, there exists δ > 0 satisfying the following: For any unital C^*-algebra A with the cancellation property,strict comparison and nonempty tracial state space, any four unitaries u₁, u₂, u₃, w ∈ A such that (1) u_ku_j - e^{2πiθjk ujukk} < δ, wu_jw^-1 = u^-1_j, w² = 1_A for j, k = 1, 2, 3; (2)τ (aw) = 0 and τ ((u_ku_ju_k^*u_j^* )ⁿ ) = e^2πinθjk for all n ∈ N, all a ∈ C^*(u₁, u₂, u₃), j, k = 1, 2, 3 and all tracial states τ on A, where C^*(u₁, u₂, u₃) is the C^*-subalgebra generated by u₁, u₂ and u₃, there exists a 4-tuple of unitaries u₁, u₂, u₃, w in A such that u_ku_j = e^2πinθjk u_ku_j, w u_j w^-1 = u^-1 _j, w² = 1A and k u_j - u_jk < ε, k w - wk < ε for j, k = 1, 2, 3. The above conclusion is also called that the rotation relations of three unitaries with the flip action is stable under the above conditions.     

关于单形的三角不等式

Theorem 1 We show that let S be a simplex in Eⁿ, its vertex angles being αi and interior dihedral angles formed by arbitrary two side faces f_i,f_j of S being Q_ij, if m_i are positive numbers (i,j= 1, 2, …, n + 1, i ≠ j), then Theorem 2 Let Ω be a simplex in Hⁿ, its interior dihedral angles formed by arbitrary two side faces F_i, F_j of Ω being φ_ij, if p_i- be positive numbers (i, j = 1,2,…., n + 1, i ≠ j), then     

一类积分算子的近于凸性

Let CS^*(α,ρ) and SB_γ(β,σ) be the subclasses of close-to-starlike functions and Bazile-vic functions class respectively. It is proved that the integral operators is close-to-convex function under the same conditions, where f_i∈CS^*(a_i,ρ_i,) and g_j∈SB_γj(β_j, σ_j). In addition, we correct a mistake in [3].     

Picard-Type Theorem and Curvature Estimate on an Open Riemann Surface with Ramification*

Let M be an open Riemann surface and G : M → Pⁿ(C) be a holomorphic map. Consider the conformal metric on M which is given by ds² = k e Gk^2m|ω|², where eG is a reduced representation of G, ω is a holomorphic 1-form on M and m is a positive integer. Assume that ds² is complete and G is k-nondegenerate(0 ≤ k ≤ n). If there are q hyperplanes H₁, H₂, · · · , H_q Pⁿ(C) located in general position such that G is ramified over H_j with multiplicity at least γ_j (> k) for each j ∈ {1, 2, · · · , q}, and it holds that Xj=1 1 -k/γ_j> (2n - k + 1) （mk/2+ 1）,then M is flat, or equivalently, G is a constant map. Moreover, one further give a curvature estimate on M without assuming the completeness of the surface.     

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.     

Formanek中心多项式的唯一构作

Formanek constructed the first central polynomial. i .e. G₁+ G₂+… + G_n where G₁= G(x, y₁,…, y_n), G₂= G(x, y₂, y₃,…, y_n, y₁) etc. Are called Forma nek's polynomials. Rosset in his nota [3] raised the question that whether all sgmmetic polynomials in G_i also give central polynomials. He showed that the basic sgmmetric polynomials in G_i are not all central. In this paper we shall show, for n≥3 each polynomial in G_j is not central, except f(G₁+ …+ G_n, where f(x)is a polynomial at x. Hence Formanek's central polynomial is unique in some sense.     

3维Poincaré猜想的一个证明

设M是一个连通闭3维流形而且π₁(M)=1,…,x_n;y₁,…,y_n>=1.在本文中，我们利用由π₁(M)=1得出来的条件x₁=y₁a₁y₁^-1…y_ka_ky_k^-1(其中y相似文献   

Duffing型方程解的有界性

证明了下列Duffing型方程的所有解的有界性 :d2x / dt2 +x²ⁿ⁺¹+Σ²ⁿ_j=0 x^jp^j(t) =0 ,n≥1,其中,p1,p2 ,… ,p2n是 1周期的有Lipschitz连续性的函数,p_n+1,… ,p2n是Zygmund连续的 .这表明Duffing型方程的解的有界性不必要求pj(t)的光滑性.