2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54444We present a brief survey of the results of the Theory of Solitons from the viewpoint of the periodic theory including some new results in the theory of 2-dimensional periodic Schrodinger Operators. The main subjects are: Periodic Solitons and Algebraic Geometry, The Theory of Solitons and the String equation, Topologically trivial and nontrivial periodic two-dimensional Schrodinger operators and Riemann surfaces and Cyclic and semicyclic chains of Laplace transformations (new results of the present author and A.Veselov).9 pages, Based on lectures delivered at the Erice Chalonge School, `String Gravity and Physics at the Planck Scale', 8-19 September 1995High Energy Physics - Theorytext