Anyone trying to refold an opened road map is wrestling with the same sort of challenges confronted by origami designers and sheet metal benders.
The problem of returning a creased sheet to its neatly folded state gets tougher when you're not sure if the sheet can be folded into a flat packet and when you're not permitted to change the crease directions. Such conundrums arise, for example, when designers determine how to bend sheet metal to produce, say, car doors or heating ducts.
Now, Erik D. Demaine of the University of Waterloo in Ontario and his coworkers have developed an efficient method for recognizing when a creased sheet indeed is foldable into a flat package.
The researchers report their results in an unpublished paper available at http://xxx.lanl.gov/abs/cs.CG/0011026.
"This represents an initial step toward developing an understanding of the three-dimensional, sheet metal- folding problem," says Joseph S.B. Mitchell of the State University of N