“…For example, it can be applied to solve constrained optimization problems (KKT Linear Systems), and also can be used in finding the solution of differential equations (see [20-22]). About this open problem, there have been some results under some certain conditions (see [10][11][12][13][14][15][16][17][18][23][24][25]). Specially, in papers [15,16,18,24], the existence and the representations of the group inverse for the following block matrices are researched: [24]); [15]);…”