Howell designs with sub-designs

J.H Dinitz, E.R Lamken
1994 Journal of combinatorial theory. Series A  
A Howell design of side s and order 2n, or more briefly an H(s, 2n), is an s x s array in which each cell is either empty or contains an unordered pair of elements from some (2n)-set V such that (1) every element of V occurs in precisely one cell of each row and each column, and (2) every unordered pair of elements from V is in at most one cell of the array. It follows immediately from the definition of an * Current address :
doi:10.1016/0097-3165(94)90024-8 fatcat:rx6aisoc75cfzl5sen5trjovji