2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/62637Let X be a K3 surface. We show that the Chow group CH_0(X) of 0-cycles contains a "fundamental class" c_X of degree 1 with remarkable properties: any product of divisors is proportional to this class, and so is the second Chern class c_2(X). This preprint supersedes the preprint math.AG/0109063 by the first author, where the latter property was conjectured.10 pages, Plain TeX. Supersedes AG/0109063Algebraic Geometrytext