On the generalized Drazin inverse in Banach algebras in terms of the generalized Schur complement

We present new results on existence and representation of the generalized Drazin inverse for elements in Banach algebras, involving the generalized Schur complement. They extend cases studied in the literature where the generalized Schur complement is assumed to be nonsingular, or zero, or group invertible. The results are applied to obtain formulas for cases of special interest.