2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/78240Let C denote any of the following cardinal characteristics of Boolean algebras: incomparability, spread, character, pi-character, hereditary Lindelof number, hereditary density. It is shown to be consistent that there exists a sequence <B_i:i<kappa> of Boolean algebras and an ultrafilter D on kappa such that C(prod_{i<kappa}B_i/D)<|prod_{i<kappa}C(B_i)/D|. This answers a number of problems posed by Monk.LogicGeneral Topology06E05, 03E35 (Primary); 03E55 (Secondary)text