In
mathematics, a
developable surface (or
torse: archaic) is a
surface with zero
Gaussian curvature. That is, it is a surface that can be
flattened onto a
plane without
distortion (i.e. "stretching" or "compressing"). Conversely, it is a surface which can be made by
transforming a plane (i.e. "folding", "bending", "rolling", "cutting" and/or "gluing"). In three dimensions all developable surfaces are
ruled surfaces (but not vice versa). There are developable surfaces in
R4 which are not ruled.