Primitive Perfect Isosceles Right Triangled Square
Title: _ 20:224AF GHM
Order: 20
Horizontal side: 224 Vertical side: 224
Elements: 1√2, 2, 2√2, 3√2, 6, 10, 10√2, 20, 16√2, 20√2, 32, 36√2, 64, 72, 64√2, 72√2, 112, 80√2, 128, 112√2.
Code: 1125 0 112 1124 112 112 806 144 144 323 144 112 162 160 128 1283 160 0 642 224 64 725 0 40 724 72 40 643 224 0 202 20 20 364 36 4 203 20 0 102 30 10 103 30 0 65 30 4 22 32 2 34 33 1 23 32 0 12 33 1
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)