2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/218959We propose a categorical setting for the study of the combinatorics of rational numbers. We find combinatorial interpretation for the Bernoulli and Euler numbers and polynomials.Adv. in Appl. Math. (2007), doi:10.1016/j.aam.2006.12.006CombinatoricsCategory Theorytext