Primitive Perfect Isosceles Right Triangled Square

Title: _d 19:146AM GHM

Order: 19

Horizontal side: 146 Vertical side: 146

Elements: 4√2, 8, 8√2, 14, 12√2, 17, 14√2, 20, 24, 17√2, 20√2, 31, 24√2, 49, 61, 73, 85, 61√2, 73√2.

Code: 855 0 61 734 73 73 733 146 73 124 85 61 40 97 73 491 146 73 80 93 69 81 101 69 142 115 55 617 0 61 610 61 61 204 81 41 203 101 41 143 115 41 315 115 24 174 98 24 173 115 24 244 122 0 243 146 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)