Primitive Perfect Isosceles Right Triangled Square

Title: __ 19:236AF GHM

Order: 19

Horizontal side: 236 Vertical side: 236

Elements: 12, 12√2, 24, 36, 46, 36√2, 37√2, 58, 60, 44√2, 74, 58√2, 60√2, 88, 67√2, 104, 74√2, 88√2, 132.

Code: 885 0 148 884 88 148 1323 176 104 607 176 236 606 176 176 362 212 140 742 74 74 444 44 104 363 212 104 245 212 116 125 212 104 124 224 104 586 178 58 674 111 37 1043 178 0 467 178 104 743 74 0 372 111 37 585 178 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)