摘要
The necessary and sufficient conditions for the small norm perturba- tion of a Drazin invertible operator to be still Drazin invertible and the sufficient conditions for the finite rank perturbation of a Drazin invertible operator to be still Drazin invertible are established.
The necessary and sufficient conditions for the small norm perturba- tion of a Drazin invertible operator to be still Drazin invertible and the sufficient conditions for the finite rank perturbation of a Drazin invertible operator to be still Drazin invertible are established.
基金
This work was supported in part by the National Natural Science Foundation of China （Crant No. 11301318） and the Science and Technology Bureau Foundation of Hangzhong （No. 2013hzzx-40）.
