A Set in Euclidean Space is convex if it contains *all* the Line Segments
connecting any pair of its points. If the Set does not contain all the Line Segments, it is
called Concave.

**References**

Croft, H. T.; Falconer, K. J.; and Guy, R. K. ``Convexity.'' Ch. A in
*Unsolved Problems in Geometry.* New York: Springer-Verlag, pp. 6-47, 1994.

© 1996-9

1999-05-25