2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/78323This paper attempts to relate some ideas of Grothendieck in his Esquisse d'un programme and some of the recent results on 2-dimensional topology and geometry. Especially, we shall discuss the Teichmüller theory, the mapping class groups, $SL(2, \bold C)$ representation variety of surface groups, and Thurston's theory of measured laminations.27 pages, 11 figures. Communications in Contemporary Mathematics, to appearGeometric TopologyAlgebraic GeometryDifferential Geometry57M(primary)text