2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/53455We study a generating function for the sum over fatgraphs with specified valences of vertices and faces, inversely weighted by the order of their symmetry group. A compact expression is found for general (i.e. non necessarily connected) fatgraphs. This expression admits a matrix integral representation which enables to perform semi--classical computations, leading in particular to a closed formula corresponding to (genus zero, connected) trees.24 pages, uses harvmac macro, 1 figure not included, Saclay preprint SPhT/92-162High Energy Physics - Theorytext