2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/141794We confirm rigorously the conjecture, based on numerical and asymptotic evidence, that all the eigenvalues of a certain non-self-adjoint operator are real.5 pagesSpectral TheoryClassical Analysis and ODEs34Lxx; 76Rxx; 34B24text