Main Page | See live article | Alphabetical index In a given set S={A} of shapes (e.g. open sets in a topological space), some shapes may be congruent to one or more others. A subset R of S is called a set of prototiles of S, if the shapes in R are mutually non-congruent R is complete in the sense that each shape A in S is congruent to one shape in this subset R. The elements of R are then called the prototiles of S. Of course any such subset R of S contains the same number of shapes. This number is called the number of prototiles of S. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.