Primitive Perfect Isosceles Right Triangled Square
Title: _ 20:456AH GHM
Order: 20
Horizontal side: 456 Vertical side: 456
Elements: 8√2, 44, 32√2, 48, 40√2, 64, 48√2, 70, 57√2, 64√2, 70√2, 114, 88√2, 96√2, 158, 114√2, 184, 171√2, 272, 228√2.
Code: 2725 0 184 2284 228 228 1716 285 285 570 285 285 441 272 228 702 342 158 701 342 228 1142 456 114 1845 0 0 964 96 88 320 192 184 404 232 144 486 224 136 1583 342 0 640 160 152 641 224 152 82 232 144 485 224 88 1143 456 0 884 184 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)