Enneagonal symmetry

Enneagonal symmetry, also known as ennic symmetry and notated as I2(9), is a 2D spherical Coxeter group. It is the symmetry group of the enneagon, with 9 rotation and 9 reflection elements.

Subgroups

 * Chiral enneagonal symmetry (maximal)
 * Triangular symmetry (maximal)
 * Chiral triangular symmetry
 * Reflection symmetry
 * Identity symmetry

Convex polytopes with I2(9) symmetry

 * Enneagon (regular)
 * Dienneagon (isogonal)/Enneambus (isotopic)