2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/223324For a connected regular scheme X, flat and of finite type over Spec(Z), we construct a reciprocity homomorphism ρ_X: C_X --> π_1^\ab(X), which is surjective and whose kernel is the connected component of the identity. The (topological) group C_X is explicitly given and built solely out of data attached to points and curves on X. A similar but weaker statement holds for smooth varieties over finite fields. Our results are based on earlier work of G. Wiesend.31 pages, corrected minor mistakes and added some remarksNumber TheoryAlgebraic Geometry19F05; 11R37text