Curves in the euclidean plane with special geometric or mechanical properties.
Curves which are not mainly described by algebraic formulas.
- Manfredo P. do Carmo: Differential Geometry of Curves and Surfaces,
Prentice-Hall Englewood Cliffs, NJ (1976).
- Alfred Gray: Modern Differential Geometry of Curves and Surfaces,
CRC Press (1994).
As a guide, polygons should be connected, no degenerate edges, no duplicate vertices.