# Reflective symmetry (diagonal)

A polyomino has *reflective symmetry over a diagonal* if it can be flipped over a diagonal line to return an identical polyomino. This type of symmetry is represented by $C_2$, the cyclic group of order 2.

A polyomino has *reflective symmetry over a diagonal* if it can be flipped over a diagonal line to return an identical polyomino. This type of symmetry is represented by $C_2$, the cyclic group of order 2.