2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/54052A review on topological strings and the geometry of the space of two dimensional theories. (Lectures given by C. Gomez at the Enrico Fermi Summer School, Varenna, July 1994)61 pages, latexHigh Energy Physics - TheoryTopology and Strings: Topics in $N=2$text