Directed PBDs with Block Sizes from K Where {4} subset of K subset of {4,...,9}

摘要

The research on directed PBDs is motivated by the construction of t-deletion/insertion-correcting codes. Fuji-Hara, Miao, Wang, and Yin have determined the existence of directed PBDs with block sizes from the set K={4,5} and the set K={4,6} completely. In this paper, we consider the cases of {4}K{4,...,9}. We settle almost completely for these cases, leaving finite values undetermined.