Contraction(2)

An affine transformation of the plane under which each point is shifted towards the -axis, parallel to the -axis, by a distance proportional to its ordinate. In a Cartesian coordinate system a contraction is given by the relations

A contraction of space towards the -plane, parallel to the -axis, is given by the relations

Comments

More usually, a contraction is defined as a transformation of a metric space that reduces distances. The notion defined above has no established name in Western literature, but is sometimes called a compression or compression-expansion.