Exterior normal

to a convex surface

A vector perpendicular to a supporting hyperplane and directed towards that half-space defined by the supporting hyperplane which does not contain the points of the surface.

Comments

Analogously one defines the exterior normal to a body; for a survey in a wider context see [a1].

References

[a1]	R. Schneider, "Boundary structure and curvature of convex bodies" J. Tölke (ed.) J.M. Wills (ed.) , Contributions to geometry , Birkhäuser (1979) pp. 13–59