Struct/The cyclic group with four elements.

=Definition=

There is a unique cyclic group, up to isomorphism, with four elements. One example is the group $(\ZZ / 4 \ZZ, +)$ of residues, mod $4$, displayed below.

=Properties=


 * The group $\ZZ / 4 \ZZ$ is an abelian group.
 * It is a cyclic group, generated by $\bar 1$.