Solvability and completeness for an electrodynamical systems that is not of Kovalevskaya type (Q1326017)

The authors consider the abstract Cauchy problem \[ A {d^ 2u \over dt^ 2} + Bu (t) = 0, \quad t>0,\;u_ 0(0) = u_ 0,\;u_ 0'(0) = u_ 1, \] where \(A\) and \(B\) are polynomials of \(d/dz\) with respect to existence, uniqueness and approximation by linear combinations of elementary solutions. There are applications to finite waveguides in radiophysics.