2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/216739A pure algebraic variant of John Roberts' field algebra construction is presented and applied to bialgebroid Galois extensions and certain generalized fusion categories.25 pages; final version, typos corrected, journal-ref addedQuantum Algebra81T05, 16W30; 16B50text