“…Again, it was extended for morphisms on arbitrary additive categories by Chen et al in [8]. More results on the Drazin inverse or the generalized Drazin inverse can also be found in [3,5,6,8,9,11,12,15]. In particular we must cite [13]: in this paper, the authors, under the commutative condition of AB = BA (when A and B are Drazin invertible linear operators in Banach spaces), gave explicit representations of (A + B) D in term of A, A D , B, and B D .…”