AZZOUZ, ABDELHALIM; MESSIRDI, BEKKAI; DJELLOULI, GHOUTI
(Bull. Math. Anal. Appl, 2011-09-01)
In this paper we give some topological conditions which ensure the closedness of the sum and product of two closed linear operators acting in a Hilbert space. We get also a general result on the formula of the adjoint (well ...