The second section discusses properties of left - invertible and right - invertible operator in use of mbekhta ' s subspaces and gives the necessary and sufficent condition . i get results as follows : theorem 2 . 6 suppose a b ( x ) is the left - invertible 第二节主要运用mbekhta子空间讨论左可逆和右可逆算子的性质，并给出算子可逆的充要条件，得到下面的定理：定理26设aeb （ x ）为左可逆算子
