Very cool! If you're just learning about the Wallpaper Groups from this and feel like you've seen them before, it is probably from the work of MC Escher [0].

Very cool! If you're just learning about the Wallpaper Groups from this and feel like you've seen them before, it is probably from the work of MC Escher [0]. If you want a great recent survey, an episode of (the inimitable and now restarted) In Our Time from last month goes into the friendship / mutual influence of Escher and Coxeter. [1] [0] https://eschermath.org/wiki/Regular_Division_of_the_Plane_Drawings.html https://eschermath.org/wiki/Regular_Division_of_the_Plane_Dr... [1] https://www.bbc.com/audio/play/m002v19c https://www.bbc.com/audio/play/m002v19c