In
mathematics, a
reflection (also spelled
reflexion) is a
mapping from a
Euclidean space to itself that is an
isometry with a
hyperplane as a set of
fixed points; this set is called the
axis (in dimension 2) or
plane (in dimension 3) of reflection. The image of a figure by a reflection is its
mirror image in the axis or plane of reflection. For example the mirror image of the small Latin letter
p for a reflection with respect to a vertical axis would look like
q. Its image by reflection in a horizontal axis would look like
b. A reflection is an
involution: when applied twice in succession, every point returns to its original location, and every geometrical object is restored to its original state.