2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/68930We construct a cover of the non-incident point-hyperplane graph of projective dimension 3 for fields of characteristic 2. If the cardinality of the field is larger than 2, we obtain an elementary construction of the non-split extension of SL_4 (F) by F^6.10 pages, 3 figuresCombinatorics05c25 (Primary) 20e22 (Secondary)text