The Quasi-Fredholm Spectrum of 2 × 2 Upper Triangular Operator Matrices

主要运用内部项的拟Fredholm性质研究了2 × 2上三角型算子矩阵的拟Fredholm谱，并拓展到无界2 × 2上三角型算子矩阵的拟Fredholm谱。给出了具体例子加以说明结论的有效性。The Quasi-Fredholm Spectrum of 2 × 2 upper triangular operator matrices is studied by using the Quasi-Fredholm property of its internal entries, and extended to the Quasi-Fredholm spectrum of the triangular operator matrices on the unbounded 2 × 2. The example is given to illustrate the validity of the result.