Primitive Perfect Isosceles Right Triangled Square

Title: _d 19:146BO GHM

Order: 19

Horizontal side: 146 Vertical side: 146

Elements: 5, 5√2, 6√2, 10, 12, 15, 12√2, 15√2, 18√2, 30, 36, 37, 30√2, 31√2, 55, 73, 55√2, 91, 73√2.

Code: 915 0 55 734 73 73 733 146 73 184 91 55 60 109 73 371 146 73 120 103 67 121 115 67 312 146 36 557 0 55 550 55 55 304 85 25 303 115 25 363 146 0 154 100 10 153 115 10 101 110 10 52 115 5 51 115 10

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)