Symmetry Group of Rhombus/Cayley Table

Cayley Table
The Cayley table of the symmetry group of the (non-square) rhombus can be written:


 * $\begin{array}{c|cccc}

& e & r & h & v \\ \hline e & e & r & h & v \\ r & r & e & v & h \\ h & h & v & e & r \\ v & v & h & r & e \\ \end{array}$