Please note: this text assumes that you have read *the article introducing the signatures and weights of tilings*.
In a wallpaper group (or wallpaper group), the same motif repeats indefinitely in both dimensions, covering the entire plane. Behind this apparent variety lies a group that transforms one basic motif into all the others. Evgraf Fedorov proved that there are exactly seventeen such groups. This is easy to prove once the plane tiling theorem is known.

The wallpaper with symbol o.

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