Primitive Perfect Isosceles Right Triangled Square
Title: _ 20:50AD GHM
Order: 20
Horizontal side: 50 Vertical side: 50
Elements: 1, 1√2, 2, 2√2, 3√2, 5, 4√2, 7, 5√2, 8, 7√2, 8√2, 13, 10√2, 16, 16√2, 24, 26, 21√2, 25√2.
Code: 267 0 50 160 26 50 161 42 50 82 50 42 81 50 50 216 29 21 100 10 34 74 17 27 73 24 27 52 29 29 51 29 34 137 29 34 46 25 25 34 20 24 10 23 27 11 24 27 20 22 26 21 24 26 250 25 25 247 0 24
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)