| Institution: | Departamento Álgebra, Geometría y Topología, Fac. Ciencias, Universidad de Málaga, Campus de Teatinos, Apdo. 59, 29080 - Málaga, Spain ; Departamento Geometría y Topología, Universidad de Granada, 18071 - Granada, Spain |
| Abstract: | The incidence relations between a Pfaffian system and the characteristic system of its first derived system lead to obtain a characterization of Pfaffian systems with derived length one. Also, for flag systems, several properties are studied. In particular, an intrinsic proof of a result which determines the class of a system and of all the derived systems is given. |
