2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/149132Lectures given at International School of Physics ``Enrico Fermi'', Varenna, Villa Monastero, June 28-July 7 199442 pages. Equation (2.6) have been corrected and explainedHigh Energy Physics - TheoryQuantum AlgebraTopics in Quantum Geometry of Riemann Surfaces: Two-Dimensional Quantum Gravitytext