Coset
Given a subgroup
likewise the right coset as
Properties
iff ( by Reärrangement lemma, by ) - As a consequence of the Reärrangement lemma
. - Cosets are either identical or disjoint.
- Every
is contained in at least one coset of , namely (by ) - From 2–4,
may be partitioned into equally sized cosets. Hence the order of a subgroup divides the order of a group.