Carleton University
Technical Report TR-00-01
January 2000
Flipping your Lid
Hee-Kap Ahn, Prosenjit Bose, Jurek Czyzowicz, Nicolas Hanusse, Evangelos Kranakis, Pat Morin
Abstract
Given a polygon P, a flipturn involves reflecting a pocket p of P through the midpoint of the lid of p. We show that any polygon on n vertices will be convex after any sequence of at most n (n – 3) / 2 flipturns. The best known previous result for this problem is due to Joss and Shannon (published in Grueunbaum (1995)) who showed any polygon is convexifi ed after at most (n – 1)! flipturns.