The first bunch of examples which illustrate these concepts will show that various important group theoretical structures can be considered as orbits or stabilizers:
.
Examples
If
denotes a group, then
acts on itself by left multiplication :
This action is called the (left)
regular representation
of
, it is obviously transitive, and all the
stabilizers are equal to the identity subgroup
.
acts on itself by conjugation :
. The orbits of this action are the
conjugacy classes
of elements,
and the stabilizers are the
centralizers
of elements:

and

(in short:
),
then
acts
on the set
of its left cosets
as follows:

This action is
transitive, and the stabilizer of
is the subgroup
which is
conjugate to
.
acts on the set
of all its subgroups
by conjugation :
. The orbits of this
action are the conjugacy classes of subgroups
, and the stabilizers are the normalizers
:

and

