2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/153816We illustrate the basic notions of {\em additional non-isospectral symmetries} and their interplay with the discrete {\em \DB transformations} of integrable systems at the instance of {\em constrained Kadomtsev-Petviashvili} (\cKP) integrable hierarchies. As a main application we present the solution of discrete multi-matrix string models in terms of Wronskian $\t$-functions of graded $SL(m,1)$ \cKP hierarchies.LaTeX, 15 pgs, To be published in Proceedings of the second Summer Workshop, Razlog/Bulgaria, Aug-Sept 1995Exactly Solvable and Integrable SystemsHigh Energy Physics - Theorytext