四元数矩阵的极分解及其GL偏序

本文给出了四元数矩阵的唯一极分解定理和两个四元数矩阵可同时极分解的两种刻画；进而引进了四元数矩阵的GL偏序的概念，它是重要的Lǒwner偏序的一般化，并得到这个新偏序的6种刻画．     

四元数矩阵的惯性定理与稳定性

本文给出了四元数矩阵惯性的定义,讨论了四元数体上Lyapunov矩阵方程的唯一解,推广了一般惯性定理、Lyapunov稳定性定理、Carlson-Schneider定理、Stein稳定性定理等一些重要的结果到四元数矩阵,同时得出了四元数体上稳定矩阵的一些判别条件.     

算子偏序的刻画及性质

本文定义了Hilbert空间上两个算子间的四种关系:星序、左星序,右星序及减序,使用了算子分块矩阵的方法,给出了两个算子具有上述四种关系之一时它们几何结构的刻画,证明了这四种关系是真正的偏序关系,进一步研究了它们之间的关系和性质.     

关于态射集中的Γ-逆与星序

研究态射集中的Г-逆的存在条件与星序的刻划．利用Г-环的方法得到了Г—Moore-Penrose逆存在的一些条件．给出了Г—Moore-Penrose逆与星序的联系以及星序的一些Г-逆刻划．     

四元数矩阵的实表示与四元数矩阵方程

四元数矩阵与四元数矩阵方程在力学和工程问题的理论研究和实际数值计算中都起到重要的作用.该文借助四元数矩阵的实表示方法,研究了一般四元数矩阵方程AXB-CYD=E的解的问题,给出了一种求解四元数矩阵方程的算法技巧.该文还得到了四元数矩阵的Roth's定理.     

分裂四元数的实表示矩阵的棣莫弗定理

依据分裂四元数的概念,首先,给出了分裂四元数的实表示矩阵形式,将对分裂四元数的研究转化为实数域上四阶矩阵的研究;其次,根据分裂四元数不同的极表示形式,得到了分裂四元数实表示矩阵相应的棣莫弗定理,推广了欧拉公式,并给出了单位分裂四元数的实表示矩阵方程的求根公式.最后,通过算例验证了结论的正确性.     

EP矩阵的Hartwig-Spindelbck 问题与ρ·M-P 逆的倒换顺序律

本文证明了体上矩阵的ρ·M-P 逆的倒换顺序律的十种刻划,给出了四元数矩阵 M-P 逆的倒换顺序律的一种新刻划,并在四元数体上解决了文献[1]中关于 EP 矩阵的两个未解问题.     

EP矩阵的Hartwig-Spindelbck 问题与ρ·M-P 逆的倒换顺序律

本文证明了体上矩阵的ρ·M-P 逆的倒换顺序律的十种刻划,给出了四元数矩阵 M-P 逆的倒换顺序律的一种新刻划,并在四元数体上解决了文献[1]中关于 EP 矩阵的两个未解问题.     

四元数体上Hermite矩阵的最小化问题

该文建立了四元数矩阵对的标准相关分解(CCD-Q). 借助CCD-Q, GSVD-Q 和有限维内积空间中的投影定理, 该文得到了基于四元数矩阵方程$AXB=C$的Hermite矩阵最小化问题解的表达式.     

四元数自共轭矩阵和的特征值的不等式

本文将Wietandt关于复自共轭矩阵的特征值和的变分特征以及和的特征值的不等式推广到四元数体上，由此还给出了复自共轭矩阵的主对角元与特征值的优化关系的Schur定理、复矩阵的主对角元的模与奇异值的优化关系的Fan定理在四元数体上的推广.     

The L* Partial Order on the Set of Group Matrices

In this paper,we use the L(o)wner partial order and the star partial order to introduce a new partial order (denoted by "L*") on the set of group matrices,and get some characteristics and properties of the new partial order.In particular,we prove that the L* partial order is a special kind of the core par-tial order and it is equivalent to the star partial order under some conditions.We also illustrate its difference from other partial orders with examples and find out under what conditions it is equivalent to other partial orders.     

A simultaneous canonical form of a pair of matrices and applications involving the weighted Moore–Penrose inverse

In this paper, a simultaneous canonical form of a pair of rectangular complex matrices is developed. Using this new tool we give a necessary and sufficient condition to assure that the reverse order law is valid for the weighted Moore–Penrose inverse. Additionally, we characterize matrices ordered by the weighted star partial order and adjacent matrices as applications.     

The diamond partial order for strong Rickart rings

The diamond partial order has been first introduced for matrices, and then discussed also in the general context of *-regular rings. We extend this notion to Rickart rings, and state various properties of the diamond order living on the so-called strong Rickart rings. In particular, it is compared with the weak space preorder and the star order; also existence of certain meets and joins under diamond order is discussed.     

A note on the star order in Hilbert spaces

We study the star order on the algebra L(?) of bounded operators on a Hilbert space ?. We present a new interpretation of this order which allows to generalize to this setting many known results for matrices: functional calculus, semi-lattice properties, shorted operators and orthogonal decompositions. We also show several properties for general Hilbert spaces regarding the star order and its relationship with the functional calculus and the polar decomposition, which were unknown even in the finite-dimensional setting. We also study the existence of strong limits of star-monotone sequences and nets.     

On a Poset of Trees II

In this article, we study problems where one has to prove that certain graph parameter attains its maximum at the star and its minimum at the path among the trees on a fixed number of vertices. We give many applications of the so‐called generalized tree shift which seems to be a powerful tool to attack the problems of the above‐mentioned kind. We show that the generalized tree shift increases the largest eigenvalue of the adjacency matrix and Laplacian matrix, decreases the coefficients of the characteristic polynomials of these matrices in absolute value. We will prove similar theorems for the independence polynomial and the edge cover polynomial. The generalized tree shift induces a partially ordered set on trees having fixed number of vertices. The smallest element of this poset is the path, largest element is the star. Hence, the above‐mentioned results imply the extremality of the path and the star for these parameters.     

New results for EP matrices in indefinite inner product spaces

In this paper we study J-EP matrices, as a generalization of EP-matrices in indefinite inner product spaces, with respect to indefinite matrix product. We give some properties concerning EP and J-EP matrices and find connection between them. Also, we present some results for reverse order law for Moore-Penrose inverse in indefinite setting. Finally, we deal with the star partial ordering and improve some results given in the “EP matrices in indefinite inner product spaces” (2012), by relaxing some conditions.