关于组合合成阵

We define the r^th combinatorial compound C_r^*(A) of a matrix A, which can be viewed as the characteristic function of the subset of the rxr submatrices of A which are combinatorially nonsingular. We prove that for 1≤rr^*(A)is. We determine the minimum number of 2×2 and 3×3 combinatorially nonsingular submatrices over all n×n fully indecomposable matrices and make a jecture for general r.     

一般Gauss—Markov模型下最小二乘估计是最佳估计的充要条件

In this paper, we discuss the decomposition of the space μ(X : V) and the invariance with respect to the choice of a generalized inverse of matrix X in the general Gauss-Markov model. In Theorem 1, we give necessary and sufficient conditions for the least squares estimator P_xy = BLUE(Xβ) under the general Gauss-Markov model M = {y,Xβ,σ²V}. In Theorem 2, we prove that P_xy= BLUE(Xβ) under model M and invariant with respect to the choice of a generalized inverse of matrix X are equivalent.     

秩减形式的一种新方法（英文）

Let A be an m by n matrix of rank l, and let M and N be m by k and n by q matrices, respectively, where k is not necessarily equal to q or rank(M AN) min(k, q). In this paper, we provide some necessary and sufficient conditions for the validity of the rank subtractivity formula: rank(A-AN(M AN)-M A) = rank(A)-rank(AN(M AN)-M A)by applying the full rank decomposition of A = F G(F ∈ Rm×l, G ∈ Rl×n, rank(A) =rank(F) = rank(G) = l) and the product singular value decomposition of the matrix pair[F M, GN ]. This rank subtractivity formula along with the condition under which it holds is called the extended Wedderburn-Guttman theorem.     

关于U统计量的一点注记

Let φ(x₁,x₂,…x_m) be a real Borel measurable symmetrical function of the m variables, and let U_n denote the U-statistic with kernel φ. In this note it is proved that the necessary and sufficient condition for E|φ|<+∞ is that there exists an n≥m such that E|U_n|< + ∞.     

Two Commuting Involutions Fixing RP1(2m + 1) S RP2(2m + 1)*

Let Z₂ denote a cyclic group of 2 order and Z₂² = Z₂ ×Z₂ the direct product of groups. Suppose that (M, Φ) is a closed and smooth manifold M with a smooth Z₂² -action whose fixed point set is the disjoint union of two real projective spaces with the same dimension. In this paper, the authors give a sufficient condition on the fixed data of the action for (M, Φ) bounding equivariantly.     

多维平稳序列与Rosenblatt推测的予报表示

In this pape we obtain a linear predictor and its error for a multidimensional, discrete parameter, full-rank and regular stationary stochastic process (S. P.) having a spectral density matrix f(λ), which mets some conditions. An example which shows that Szego-Kolmogorov's Theorem for the prediction error with lag l in terms f(λ):σ₁²=2πexp{1/(2π)∫_-x^xlogf(λ)dλ},(1) can't be formally kept true in matrix form is given.     

Generalized Steiner Triple Systems with Group Size g ≡0, 3 (mod 6)

Generalized Steirier triple systems, GS(2,3,n,g), are equivalent to maximum constant weight codes over an alphabet of size g 1 with distance 3 and weight 3 in which each codeword has length n. The necessary conditions for the existence of a GS(2,3,n,g) are (n-1)g≡0 (mod 2), n(n-1)g2≡0 (mod 6), and n≥g 2. These necessary conditions are shown to be sufficient by several authors for 2≤g≤11. In this paper, three new results are obtained. First, it is shown that for any given g, g≡0 (mod 6) and g≥12, if there exists a GS(2.3.n.g) for all n, g 2≤n≤7g 13. then the necessary conditions are also sufficient. Next, it is also shown that for any given g, g≡3 (mod 6) and g≥15, if there exists a GS(2,3,n,g) for all n, n≡1 (mod 2) and g 2≤n≤7g 6, then the necessary conditions are also sufficient. Finally, as an application, it is proved that the necessary conditions for the existence of a GS(2,3,n,g) are also sufficient for g=12,15.     

Some Conditions for Matrices over an Incline To Be Invertible and General Linear Group on an Incline

Inclines are the additively idempotent semirings in which products are less than or equal to either factor. In this paper, some necessary and sufficient conditions for a matrix over L to be invertible are given, where L is an incline with 0 and 1. Also it is proved that L is an integral incline if and only if GLn（L） = PLn （L） for any n （n 〉 2）, in which GLn（L） is the group of all n × n invertible matrices over L and PLn（L） is the group of all n × n permutation matrices over L. These results should be regarded as the generalizations and developments of the previous results on the invertible matrices over a distributive lattice.     

Classification of Quasifinite Modules with Nonzero Central Charges for EALAs of Type A with Coordinates in Quantum Torus

The author first constructs a Lie algebra ∑ ：=∑（q, Wd） from rank 3 quantum torus, which is isomorphic to the core of EALAs of type Ad-1 with coordinates in quantum torus Cqd, and then gives the necessary and sufficient conditions for the highest weight modules to be quasifinite nonzero central charges are Finally the irreducible Z-graded quasifinite ∑-modules with classified.     

ON THE ASYMPTOTIC ASSIGNMENT OF THE BOUNDS OF DECREASING RATE FOR A TIME-VARYING LINEAR CONTROL SYSTEM

In the paper the problem on the assignment of the bounds of decreasing rate for a time-varying linear control system is discussed. The sufficient and necessary condition for bounds of decreasing rate of a time-varying linear system to be assigned arbitrarily is presented. It is pointed out that for any given real number n, M, n相似文献