2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55698Review of some old and relatively new ideas surrounding the subjects of AdS/CFT correspondence, generalized tau-functions and possible equivalences between a priori different quantum field theories.LaTeX, 17pp. Talk given at INTAS-RFBR School, September 98High Energy Physics - Theorytext