“…(2.9) The condition (2.9) appears in many recent works on semilinear wave equations with memory (e.g. [13]) and the strongly damped wave equation (this condition refers to the subcritical setting of those problems), see for example [2,3,12,21,25,28,29]. By (2.8) we find that for some α ∈ (0, λ 1 ), there exists ρ f > 0 so that, for all s ∈ R, there hold…”