FpGroup( G )
computes a finite presentation of the CrystGroup G, and binds it to
G.fpGroup. If the point group (and thus G) is solvable, a
power-commutator presentation is returned. The presentation is always
an extension of the presentation of the point group (which is computed
if necessary).
Warning: The abstract generators of the presentation are not More about Crystallographic Groups).
GAP 3.4.4