Let Mc = ( A0CB ) be a 2 × 2 upper triangular operator matrix acting on the Banach space X × Y. We prove that σr(A) ∪ σr( B)= σr (Mc) ∪ W ,where W is the union of certain of the holes in σr(Mc) which happen to be subsets of σr(A) ∩ σr(B), and σr(A), σr(B), σr(Mc) can be equal to the Browder or essential spectra of A, B, Mc, respectively. We also show that the above result isn't true for the Kato spectrum, left (right) essential spectrum and left (right) spectrum.
In this paper we discuss the K-groups of Wiener algebra ;W. For the 1-shift space XGM2,We obtain a characterization of Fredholm operators on X^nGM2 for all n ∈ N. We also calculate the K-groups of operator algebra on the 1-shift space XGM2.