摘要
Ⅰ. INTRODUCTIONCauchy’s problems and mixed problems of hyperbolic equations of the second order and the higher order were studied previously. Some papers, such as [3] and [4], were devoted to the study on the Dirichlet problem of the hyperbolic equation of the second order. There still remain some questions: Might any boundary value problem for the hyperbolic equation of the higher order be posed? What difference would appear between them?
