Grebs Frieze, Ben Youssef Madrasah

• The symmetry group of the tiling is *442 (p4m).
• All the internal angles of the constituent polygons are a multiple of 15°.
• Contains three regular 12-pointed star polygons with vertex angle of 60°.
• There are 9 non-regular reflective tiles (including one kite).
• The tiling satisfies the interlace condition and has one finite interlace and one infinite interlace with straight cross-overs.
• The tiling is edge-to-edge.
• As drawn, contains about 679 polygons.

1. Page 236, top left (Ben Youssef Madrasah, Marrakesh, Morocco. Grebs Frieze) of Jean-Marc Castéra. Arabesques: Decorative Art in Morocco, ACR Edition, Paris, 1999. ISBN 286770124. [castera] {Beautiful book.}(14th century AD)
2. Photo by David Wade: MOR 1236 (Ben Youssef Madrasah, Marrakesh, Morocco) of David Wade. Website: patterninislamicart.com, UK, 2015. [wadei] {Website}

• Wade photo MOR 1236

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