讲座内容：

Let (G,+) be a group of order v, k and λ be positive integers such that 2≤k≤v. A (v,k,λ)-difference packing (briefly DP) over G is a collection 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 λ times. The set λG\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 result of 1-rotational balanced incomplete block designs with block size 4 and any index λ>1 is presented.