 Two physicists , Peter J. Lu and Paul Steinhardt , attracted controversy in 2007 by claiming that girih designs such as that used on the Darb @-@ e Imam shrine in Isfahan were able to create quasi @-@ periodic tilings resembling those discovered by Roger Penrose in 1973 . They showed that rather than the traditional ruler and compass construction , it was possible to create girih designs using a set of five " girih tiles " , all equilateral polygons , secondarily decorated with lines ( for the strapwork ) . 
