On the Cauchy problem for equations with multiple characteristic roots
On the Cauchy problem for equations with multiple characteristic roots
1.8)$(L_{0}+B)u=f$ is not well posed in $L^{2}$ sense for any lower order operator $B$ .REMARK.In Theorem 1.1, we assume that (1.7) has real roots for any real $\xi\neq 0$ .We notice here that if the Cauchy problem for (1.1) is well posed in $L^{2}$ sense, then the roots of (1.7) …