Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:339AB GHM

Order: 20

Horizontal side: 339 Vertical side: 339

Elements: 10, 10√2, 34, 34√2, 53, 57, 45√2, 68, 53√2, 63√2, 90, 68√2, 102, 106, 90√2, 135, 136, 102√2, 170, 237.

Code: 2377 0 339 1063 237 233 1027 237 339 1026 237 237 575 237 180 630 131 233 534 184 180 533 237 180 104 194 170 103 204 170 902 294 90 901 294 180 452 339 135 686 0 102 1367 68 170 1703 204 0 1353 339 0 685 0 34 345 0 0 344 34 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)