The following sections describe how one can compute the right, left, and double cosets of subgroups (see RightCosets, LeftCosets, DoubleCosets). Further sections describe how cosets are created (see RightCoset, IsRightCoset, LeftCoset, IsLeftCoset, DoubleCoset, Set Functions for Right Cosets, Right Cosets Records, Set Functions for Double Cosets, and Double Coset Records).
A coset is a GAP domain, which is different from a group. Altough the
set of elements of a group and its trivial coset are equal, the group
functions do not take trivial cosets as arguments. A trivial coset must
be convert into a group using AsGroup (see AsGroup) in order to be
used as group.
GAP 3.4.4