A Galvagni figure is a figure that can be tiled by a polyform in more than one way—a kind of self-compatibility figure. A Reid figure is a Galvagni figure with no holes. Galvagni figures first appeared in Erich Friedman's Math Magic for November 2004.
Here are minimal known Galvagni figures and Reid figure for polyhops. The black tiles have no solution. The gray tiles have no known solution.
Last revised 2012-02-24.