# the Alhambra

Topic:
Symmetry

## Symmetry groups

Marcus du Sautoy calls the Alhambra ‘the palace of symmetry' and describes how he walks through the Alhambra with his son and a list of wallpaper groups. The people who decorated the 14th century weren’t aware of a theoretical concept of 17 possible groups but they managed to apply them all. Room after room, wall after wall they surprize the visitor with just a new variation, establishing another pattern.

## unit repeat

De Islamic decorators knew which regular forms to use to create tilings and used squares, rhombuses, parallelograms, triangles and hexagons as unit repeats. They created tilings using all kinds on transformations on this unit repeat.

## GeoGebrabooks

I created some GeoGebrabooks in dutch on the Alhambra: - symmetrie in het Alhambra - behangpapiergroepen (wallpapergroups) - Alhambra met passer, lineaal en GeoGebra - Escher en het Alhambra

## Ernest Hanbury Hankin - other practices

Ernest Hanbury Hanking (1865 - 1939) was a British biologist working in colonial British-India. Apart of his studying on diseases as malaria and cholera he was also interested in Islamic patterns on the monuments of Mogul emperors from the 15th until the 18th century. In 1925 Hanking publishes an article on what he calls 'The Drawing of Geometric Patterns in Saracenic Art'. You can find it online at Geometric Patterns. It was the first western report on the technique of creating line patterns by the use of an underlying tesselation of polygons.