# Wallpaper Groups

### Symmetry group 10 (p4)

This is the first group with a 90° rotation, that is, a rotation of order 4. It also has rotations of order 2, that is, half-turns. The centers of the half-turns are midway between the centers of the order-4 rotations. There are neither reflections nor glide-reflections. The lattice is square, and a quarter of a square fundamental region for the translation group is a fundamental region for the symmetry group.

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© 1994, 1997.

David E. Joyce

Department of Mathematics and Computer Science

Clark University

Worcester, MA 01610

These files are located at http://aleph0.clarku.edu/~djoyce/wallpaper/