A note on the representation for the Drazin inverse of block matrices

In this note we consider representations of the Drazin inverse of 2×2 block matrices under conditions weaker than those used in recent papers on the subject, in particular in [D.S. Djordjević, P.S. Stanimirović, On the generalized Drazin inverse and generalized resolvent, Czechoslovak Math. J. 51 (126) (2001) 617–634; R. Hartwig, X. Li, Y. Wei, Representations for the Drazin inverse of 2×2 block matrix, SIAM J. Matrix Anal. Appl. 27 (2006) 757–771].     

Representations for the Drazin inverses of 2 × 2 block matrices

Let M denote a 2 × 2 block complex matrix , where A and D are square matrices, not necessarily with the same orders. In this paper explicit representations for the Drazin inverse of M are presented under the condition that BDⁱC = 0 for i = 0, 1, … , n − 1, where n is the order of D.     

G-函数与分块阵的特征值分布

利用由Nowosad和Hoffman提出的G-函数概念来刻划分块阵的特征值分布，对块对角占代性进行了G-函数推广，并研究它们的本质联系，获得了分块阵特征值若干包含域，以及M矩阵的充分条件．所得结果较已有结果，明显具有一般性．     

Expression of the Drazin and MP-inverse of partitioned matrix and quotient identity of generalized Schur complement

In this paper we give representations of the Drazin and MP-inverse of a 2×2 block matrix and quotient identities for the generalized Schur complement of a partitioned 3×3 matrix under conditions different than those used in recent papers on the subject. We present numerical examples to illustrate our results.     

一类缺项算子矩阵的谱补问题

对于Hilbert空间上的2×2算子矩阵，其中A∈B（H），C∈B（K，H），D∈B（H，K）给定，当X取遍B（K）中算子时，我们给出所有Nx的谱之交集和并集的刻画．     

利用分块矩阵对两个结论的进一步推广

利用分块矩阵的知识,将高等代数中两道在文献[3]中已推广的结论作了进一步的推广证明,使对原有习题成立的充分条件加强到充要条件.并用新方法给出了证明.