MergedIgs( U, S, gens, normalize )
Let U and S be ag groups with a common parent group G such that S
is a subgroup of U. Let gens be a list of elements of U. Then
MergedIgs returns the subgroup K of G generated by S and gens.
As gens contains only elements of U, the subgroup K is not only a
subgroup of G but also of U. Its parent group is nevertheless G
and MergedIgs computes a induced generating system of S with respect
to G.
If normalize is true, a canonical generating system for K is
computed and bound to K.cgs. If normalize is false only an
induced generating system is computed and bound to K.igs or
K.cgs. If no subgroup S is known, rec() can be given instead.
Note that U must be an ag group which contains S and gens.
GAP 3.4.4