Primitive Perfect Isosceles Right Triangled Square
Title: _ 20:160BJ GHM
Order: 20
Horizontal side: 160 Vertical side: 160
Elements: 12, 12√2, 20, 15√2, 24, 18√2, 20√2, 30, 24√2, 40, 42, 30√2, 48, 40√2, 41√2, 60, 45√2, 59√2, 60√2, 100.
Code: 1005 0 60 594 59 101 180 118 160 421 160 160 416 59 101 127 100 142 126 100 130 247 112 142 240 136 142 452 145 85 481 160 118 150 145 85 300 130 70 301 160 70 607 0 60 600 60 60 204 80 40 203 100 40 404 120 0 403 160 0
The properties below may precede order:side in a tiling's title:
- c = crossed. There is a tile-corner traversed by two lines. The only known crossed PPIRTS's below order 20 are 19:35AB1of4 and 19:35AB4of4.
- d = double-pentagon patterned. Every such tiling is a subdivision of an instance of the same deformable tiling by two 45-90-90-90-225 pentagons with a shared side, four triangles and two pseudotriangles. All below order 19 are degenerate in the sense that one or more sides of underlying tiles have shrunk to zero length. The non-degenerate d-tilings of order 19 are 19:221AA, 19:229AB and 19:241AA.
- e = elegant. No tile-corner is just a T-junction. Such tilings may be considered aesthetically pleasing. The only known elegant PPIRTS's below order 16 are 13:21AA, 14:26AJ, 14:35AA and 15:55AA.
- i = isomers exist which are ineligible for this catalogue. They are not included in the isomer count which follows 'of' in the tiling id.
- r = rectangular inclusion. The only known PPIRTS's below order 16 with a rectangular inclusion are 13:18AA1-4of4 and 15:44AA1-4of4.
Credit for Discovery
Just three people are credited with the discovery of Primitive Perfects:
Geoffrey H. Morley (GHM, England)
Jasper D. Skinner, II (JDS, United States)
William T. Tutte (WTT, Canada, 1917-2002) (15:44AI, 17:136AJ and 19:56AJ only)