Abstract: | In this article, we construct a (6p, 5, 1) cyclic difference matrix with one hole of size 6 for any prime p > 5 and a (2p, 5, 1) cyclic difference matrix with one hole of size 2 for any prime p ≡ 1, 13 or 17 (mod 24). © 2006 Wiley Periodicals, Inc. J Combin Designs 14: 391–399, 2006 |