On the well-posedness of the mixed problem for hyperbolic operators with characteristics of variable multiplicity

The paper is devoted to the study of the well-posedness of the mixed problem for hyperbolic equations with constant coefficients and characteristics of variable multiplicity. The authors distinguish a class of higher-order hyperbolic operators with constant coefficients and characteristics of variable multiplicity for which a generalization of the Sakamoto $L_2$-well-posedness of the mixed problem is obtained.