The FGA package provides methods for computations with finitely
generated subgroups of free groups.
It allows you to (constructively) test membership and conjugacy, and to
compute free generators, the rank, the index, normalizers, centralizers,
and intersections where the groups involved are finitely generated
subgroups of free groups.
In addition, it provides generators and a finite presentation for the
automorphism group of a finitely generated free group and allows to
write any such automorphism as word in these generators.