Primitive Perfect Isosceles Right Triangled Square

Title: _d 19:150BC GHM

Order: 19

Horizontal side: 150 Vertical side: 150

Elements: 1√2, 6, 6√2, 12, 12√2, 13√2, 14√2, 25, 19√2, 28, 30, 31, 28√2, 47, 61, 75, 61√2, 89, 75√2.

Code: 895 0 61 754 75 75 753 150 75 144 89 61 136 90 62 192 122 56 471 150 75 10 90 62 617 0 61 610 61 61 301 91 61 122 103 49 253 122 31 282 150 28 123 103 37 65 91 31 64 97 31 311 122 31 283 150 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)