Resumen de Generating pairs and group actions
Anactionofafinitegrouponaclosed2-manifoldiscalledalmostfreeifithasasingleorbitofpointswithnontrivialstabilizers.Itiscalledlargewhentheorderofthegroupisgreaterthanorequaltothegenusofthesurface.Weprovethattheorientation-preservinglargealmostfreeactionsofGonclosedorientablesurfacescorrespondtotheNielsenequivalenceclassesofgeneratingpairsofG.Weclassifythealmostfreeactionsonthesurfacesofgenera3and4,findthelargealmostfreeactionsofthealternatinggroupA5,andgivevariousotherexamples.
