Proceedings of the 18th Annual Canadian Conference on Computational Geometry, CCCG 2006
Every simple planar polygon can undergo only a finite number of pocket flips before becoming convex. Since Erdős posed this as an open problem in 1935, several independent purported proofs have been published. However, we uncover a plethora of errors and gaps in these arguments, and remedy these problems with a new (correct) proof.
© the authors
Demaine, Erik D.; Gassend, Blaise; O’Rourke, Joseph; and Toussaint, Godfried T., "Polygons Flip Finitely: Flaws and a Fix" (2006). Computer Science: Faculty Publications, Smith College, Northampton, MA.