2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/139043We study the sets of the infinite sentences constructible with a dictionary over a finite alphabet, from the viewpoint of descriptive set theory. Among other things, this gives some true co-analytic sets. The case where the dictionary is finite is studied and gives a natural example of a set at the level omega of the Wadge hierarchy.LogicGeneral Topology03E15, 03B70, 54H05, 68Q45, 68R15text