With the Penrose tiling, you can add features to the edges of the tiles which enforce the extra placement rules, so it was the first time a set of 2 tiles which

With the Penrose tiling, you can add features to the edges of the tiles which enforce the extra placement rules, so it was the first time a set of 2 tiles which tile the plane only aperiodically was known. https://en.wikipedia.org/wiki/Penrose_tiling#Rhombus_tiling_(P3) https://en.wikipedia.org/wiki/Penrose_tiling#Rhombus_tiling_...