Table 3.
Typical Irish tetrahedra
Points | Irish high: 8 symmetries |
Irish medial: 3 symmetries |
Irish low: 2 symmetries |
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---|---|---|---|---|---|---|
Coordinates | Type | Coordinates | Type | Coordinates | Type | |
Vertices | (−1/4, 1/2, 0) | + | (0, 0, 0) | 0 | (0, 0, 0) | + |
(1/4, 1/2, 0) | + | (0, 1/4, 1/2) | + | (−1/4, 1/2, 0) | + | |
(0, 1/4, 1/2) | + | (1/2, 0, 1/4) | + | (1/4, 1/2, 0) | + | |
(0, 3/4, 1/2) | + | (1/4, 1/2, 0) | + | (0, 1/4, 1/2) | + | |
Node | (0, 1/2, 1/4) | − | (5/24, 5/24, 5/24) | 03 | (−5/32, 0, 10/32) | −0 |
Dodecahedral cells have nuclei 0, 1, 2, or 3 and volume 125/1024. Dodecadihedral ones have nuclei + and volume 129/1024. Here 03 = (7/12)·0 + (5/12)·3 and −0 = (5/8)·− + (3/8)·0. Nodes are all points −, 01, 12, 23, 30, 03, 10, 21, 32, −0, −1, −2, or −3 with above proportions.