Turning a sphere inside out without allowing any sharp creases along the way is a tricky mathematical maneuver. Carving an intricate snow sculpture depicting a crucial step in this twisty transformation presents its own difficulties.
This was the challenge facing a team led by mathematician Stan Wagon of Macalester College in St. Paul, Minn., last month at the 14th International Snow Sculpture Championship in Breckenridge, Colo.