… We show the exponential decay of certain 2 2 operator matrix semigroups in Hilbert
spaces. Applications are given to several damped wave equations. … Huang studied the
exponential decay of certain matrix semigroups. By applying his results to abstract second
order Cauchy problems and damped wave equations he obtained estimates for the …
Since the assumptions on B and C imply that A0 is dissipative we conclude by the Lumer{Philips
theorem that A generates a contraction semigroup. By Theorem 1.2 this …