Primitive Perfect Isosceles Right Triangled Square

Title: _ 20:192AX GHM

Order: 20

Horizontal side: 192 Vertical side: 192

Elements: 2, 2√2, 26, 19√2, 30, 22√2, 32, 25√2, 26√2, 38, 44, 50, 38√2, 60, 44√2, 50√2, 66√2, 94, 98, 96√2.

Code: 985 0 94 964 96 96 666 126 126 303 126 96 442 170 82 24 98 94 23 100 94 262 126 70 261 126 96 945 0 0 504 50 44 503 100 44 443 170 38 222 192 60 323 126 38 603 192 0 254 75 19 196 75 19 385 94 0 384 132 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)