2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/149147The two-dimensional non-linear sigma model approach to Self-dual Yang-Mills theory and to Self-dual gravity given by Q-Han Park is an example of the deep interplay between two and four dimensional physics. In particular, Husain's two-dimensional chiral model approach to Self-dual gravity is studied. We show that the infinite hierarchy of conservation laws associated to the Husain model carries implicitly a hidden infinite Hopf algebra structure.19, Phyzzx, no figures, major revisions and changes in the above versionHigh Energy Physics - TheoryGeneral Relativity and Quantum Cosmologytext