2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/80988The method of obtaining new integrable coupled equations through enlarging spectral problems of known integrable equations, which was recently proposed by W.-X. Ma, can produce nonintegrable systems as well. This phenomenon is demonstrated and explained by the example of the enlarged spectral problem of the Korteweg - de Vries equation.11 pagesExactly Solvable and Integrable SystemsMathematical PhysicsAnalysis of PDEstext