Editing Pseudo-differential operator (section)

==Kernel of pseudo-differential operator==

Pseudo-differential operators can be represented by [[Integral transform|kernels]].  The singularity of the kernel on the diagonal depends on the degree of the corresponding operator. In fact, if the symbol satisfies the above differential inequalities with m ≤ 0, it can be shown that the kernel is a [[Singular integral|singular integral kernel]]. <!--The kernels are used for characterization of boundary data for inverse boundary problems.-->