2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/149085I review some of the recent progress in two-dimensional string theory, which is formulated as a sum over surfaces embedded in one dimension.76 pages, Phyzzx, lectures at the 1991 ICTP Spring School; v2: postscript figures includedHigh Energy Physics - Theorytext