2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/148397Let \E : 0 --> S --> E --> Q --> 0 be a short exact sequence of hermitian vector bundles with metrics on S and Q induced from that on E. We compute the Bott-Chern form of \E corresponding to any characteristic class, assuming E is projectively flat. The result is used to obtain a new presentation of the Arakelov Chow ring of the arithmetic grassmannian.22 pages, LaTex, fonts corrected, to appear in L'Enseignement MathematiqueAlgebraic Geometrytext