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| | The Diamond Theorem |
 | | Among the 35 structures of the 840 4x4 arrays of tiles, orthogonality (in the sense of Latin-square orthogonality) corresponds to skewness of lines in the finite projective space PG(3,2). |
 | | The proof uses a decomposition technique for functions into a finite field that might be of more general use. |
 | | The underlying geometry of the 4x4 patterns is closely related to the Miracle Octad Generator of R. Curtis-- used in the construction of the Steiner system S(5,8,24)-- and hence is also related to the Leech lattice, which, as Walter Feit has remarked, "is a blown up version of S(5,8,24)." |
| diamondtheorem.com (717 words) |
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