2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/138261It is shown that if A generates a bounded cosine operator function on a UMD space X, then i(-A)^{1/2} generates a bounded C_0-group. The proof uses a transference principle for cosine functions.16 pages, research articleFunctional Analysis47A60; 47D06text