Proper noun
Bruck-Ryser-Chowla theorem
(mathematics) A result on the combinatorics of block designs, stating that, if a (v, b, r, k, λ)-design exists with v = b (a symmetric block design), then: (i) if v is even, then k − λ is a square; (ii) if v is odd, then the following Diophantine equation has a nontrivial solution: x − (k − λ)y − (−1) λ z = 0.