2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/125230This article deals with a study of the structure of the class group of the cyclotomic field $K=\Q(ζ_p)$ for $p$ an odd prime number, starting from Stickelberger relation. The present state of this work leads me to set a question for all the prime numbers $h\not=p$ which divide the relative class number $h^-(K)$.The title is modified. The section 4 is removed because it contains an irrecoverable error: It is not possible to use epsilon_chi U_p instead of epsilon_chi U. The section 4 is consequently removedNumber Theory11R18; 11R29; 11R23text