returns the subgroup of group for which the images of the points are still in the list .
returns the setwise stabilizer subgroup under the action given by the function f.
- Group elements in the setwise stabilizer do not necessarily fix the points .
- The pointwise stabilizer of a list of points, computed with GroupStabilizer, is a subgroup of the setwise stabilizer of the same list of points.
- The output is a subgroup of group defined by generators, but possibly using different generators.
- Evaluation of for an action function f, a point p and a permutation g of the given group, is assumed to return another point p'.
- For permutation groups, the default group action is taken to be PermutationReplace.