## Branching of singularities for some second or third order microhyperbolic operators

J. Math. Sci. Univ. Tokyo
Vol. 2 (1995), No. 3, Page 671--749.

Yamane, Hideshi
Branching of singularities for some second or third order microhyperbolic operators
We study microhyperbolic operators of the form $(D_1 - Î±_1 x_1 D_n)(D_1 - Î±_2 x_1 D_n)$+lower, $(D_1 - x_1 D_n)D_1(D_1 + x_1 D_n)$+lower. When the lower order terms take a certain form, we can obtain a very detailed information about the singularity of a solution. We look at this problem from the viewpoint of boundary value problems. General arguments for $m$-th order operators are given.