Primitive Perfect Isosceles Right Triangled Square

Title: __ 19:139AC GHM

Order: 19

Horizontal side: 139 Vertical side: 139

Elements: 1, 1√2, 2, 3, 3√2, 5√2, 16, 16√2, 32, 29√2, 30√2, 43, 32√2, 48, 43√2, 64, 48√2, 80, 91.

Code: 917 0 139 320 91 139 321 123 139 162 139 123 161 139 139 803 139 43 306 29 77 647 59 107 290 29 77 487 0 48 480 48 48 54 53 43 23 58 46 12 59 47 13 59 46 30 56 46 31 59 46 434 96 0 433 139 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)