Spectra and Fine Spectra of Lower Triangular Double-Band Matrices as Operators on Lp (1 ≤ p < ∞)

Let Δa,b denote an infinite lower triangular double-band matrix. In this paper, the spectrum, the point spectrum, the continuous spectrum and the residual spectrum of the matrix Δ_a,b as a linear operator on the sequence space l_p, where 1 ≤ p < ∞ are characterized completely