讲座内容：

Let (G,+) be a group of order v and k be positive integer such that 2≤k≤v. A (v,k,1)-difference packing (briefly DP) over G is a set Ɓ of k-subsets of G (called base blocks) such that the multiset

ΔƁ:=∪_{B∈Ɓ} ΔB:=∪_{B∈Ɓ} {y-y': y, y'∈B, y≠y'}

covers every non-zero element of G at most once. The set G\ΔƁ is called the difference leave of this DP. In this talk the existence results on (v,k,1)-DP over G are summarized. As applications, the existence of an optimal (v,4,1)-optical orthogonal code achieving the Johnson bound are presented. We also give applications of our results to cyclic balanced sampling plan avoiding adjacent units (cyclic BSA) and cyclic balanced incomplete block design (cyclic BIBD) with index.greater than 1.