Dihedral Groups

Dihedral Group

A dihedral group $D_{2n}$ is the group of symmetries of a regular $n$-sides polygon, which includes rotations and reflections with order $2n$: $D_{2n}=⟨r,s\mid r^n,s^2,(sr{)}^2⟩$

Prop $D_1$ and $D_2$ are the only abelian dihedral groups.