Graduate School of Mathematical Sciences, The University of Tokyo
Journal of Mathematical Sciences, The University of Tokyo. Vol. 7 (2000), No. 3, Page 401-422
We prove that a second-microlocal version of the Sato-Kashiwara determinant computes the Newton polygon of determined systems of linear partial differential operators with constant multiplicities. Applications are given to the Cauchy problem for hyperbolic systems with regular singularities.