Primitive Perfect Isosceles Right Triangled Square
Title: _ 20:394AA GHM
Order: 20
Horizontal side: 394 Vertical side: 394
Elements: 5√2, 36, 34√2, 36√2, 68, 82, 92, 68√2, 100, 82√2, 118, 84√2, 128, 92√2, 100√2, 174, 128√2, 184, 133√2, 138√2.
Code: 1382 138 256 1334 133 261 1280 266 394 1281 394 394 56 133 261 827 138 266 820 220 266 1741 394 266 366 102 220 686 34 152 365 102 184 1005 102 84 1004 202 84 1843 302 0 922 394 92 346 0 118 685 34 84 1185 0 0 923 394 0 844 118 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)