2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/150942In this paper we solve positively the problem of (local) density of the "potentials" M(x,y) of the Moutard equation, u_{xy} = M(x,y) u, u=u(x,y), (used in many papers for construction of exact solutions of (2+1)-dimensional integrable systems) obtainable from a given initial potential with consecutive Moutard transformations.6 pages (17 Kbytes), standard LaTeX 2.09, run twice to get the right cross-references. Resubmitted with the only correction: acknowledgment of grant RBFR 96-01-00050 supportExactly Solvable and Integrable Systemstext