“…where (α, β) ∈ [0, 1] × [0, 1], γ 1 ∈ R\{0}, γ 2 ∈ R + , and A denotes a self-adjoint operator on a Hilbert space. The regularity analysis for (1.1) have been developed in [1,2,3,7,10,11,13,14,23,24], where the semigroup associated with the system is analytic, of specific order Gevrey classes, and nonsmoothing have been obtained. Moreover, L p -resolvent estimates and time decay estimates for the solutions in the L q norm with q ∈ [2, ∞] have been derived [7].…”