2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/72006The paper has been withdrawn by the author as the main technical result (Th. 4.6) is false, as well as Corol. 4.3 on which it is based. The question of oscillation stability of the Urysohn space remains therefore open.This paper has been withdrawn by the authorFunctional Analysistext