Primitive Perfect Isosceles Right Triangled Square
Title: _ 20:292AR GHM
Order: 20
Horizontal side: 292 Vertical side: 292
Elements: 4, 4√2, 8, 7√2, 8√2, 14, 16, 14√2, 16√2, 28√2, 44√2, 88, 72√2, 102, 116, 88√2, 95√2, 102√2, 176, 190.
Code: 1905 0 102 1761 176 292 722 248 220 1161 292 292 440 248 220 286 176 148 887 204 176 886 204 88 162 192 132 163 192 116 82 200 124 83 200 116 42 204 120 43 204 116 144 190 102 143 204 102 1025 0 0 1024 102 0 76 197 95 950 197 95
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)