2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/79323Some completely positive maps on reduced amalgamated free products of C*-algebras are constructed; these allow a proof that the class of exact unital C*-algebras is closed under taking reduced amalgamated free products. Consequently, the class of exact discrete groups is closed under taking amalgamated free products.21 pagesOperator Algebras46L05; 46L35text