2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/102299A family C of circuits of a matroid M is a linear class if, given a modular pair of circuits in C}, any circuit contained in the union of the pair is also in C. The pair (M,C) can be seen as a matroidal generalization of a biased graph. We introduce and study an Orlik-Solomon type algebra determined by (M,C). If C is the set of all circuits of M this algebra is the Orlik-Solomon algebra of M.10 pages. Port. Math. to appearCombinatorics05B35; 14F40text