Oscillation criteria of yan type for linear hamiltonian systems

New oscillation criteria of Yan type are established for the linear Hamiltonian system X X′ = A(t)X + B(t)Y,t ≥ t0, Y′ = C(t)X − A*(t)Y, where A(t), B(t), and C(t) are continuous n × n-matrix valued functions with B*(t) = B(t) > 0, C*(t) = C(t). The criteria obtained generalize and improve some previous results for the second-order linear matrix differential systems in literature.