Directed B(K, 1; v) with K = {4, 5} and {4, 6} related to deletion/insertion‐correcting codes

Motivated by the construction of t‐deletion/insertion‐correcting codes, we consider the existence of directed PBDs with block sizes from K = {4, 5} and {4, 6}. The spectra of such designs are determined completely in this paper. For any integer {υ ≥ 4, a DB({4,5} ,1; υ) exists if and only if υ∉{6, 8, 9, 12, 14}, and a DB({4, 6}, 1; υ) exists if and only if υ ≡ 0,1 mod 3 and υ∉{9,15}. © 2001 John Wiley & Sons, Inc. J Combin Designs 9: 147–156, 2001