Primitive Perfect Isosceles Right Triangled Square

Title: __ 19:208AP GHM

Order: 19

Horizontal side: 208 Vertical side: 208

Elements: 5√2, 10, 10√2, 15√2, 19√2, 30, 22√2, 38, 30√2, 44, 38√2, 60, 66, 82, 60√2, 88, 63√2, 126, 104√2.

Code: 1265 0 82 1044 104 104 606 148 148 443 148 104 605 148 88 224 126 82 663 148 38 305 148 58 304 178 58 883 208 0 825 0 0 634 63 19 102 158 48 154 163 43 103 158 38 52 163 43 196 63 19 385 82 0 384 120 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)