|
In mathematics, reflection (also spelt
reflexion) refers to an involutive automorphism of a space which leaves
invariant a subspace of codimension 1. (This means that a two-dimensional (n dimensional) space is
flipped around a one-dimensional (n-1 dimensional)axis within that space.)
Note that this applies to more than just Euclidean geometry.
Reflections in affine geometry with respect to a given hyperplane is not unique, for example. Also, an inversion in inversive geometry is considered a
reflection by this definition.
In algebra, especially relational algebra, a relation R is reflexive if, for any x,
- x R x
E.g. equality is reflexive because
- x = x.
See also: Coordinate rotations and reflections.
This article is a stub. You can
help Wikipedia by expanding it .
|