“…It can be easily veriÿed that (V; B) forms a balanced incomplete block design over V = Z 5 ∪ {∞}, with block size k = 4, and = 12. We partition each block of B into 3 subblocks of size 2; 1 and 1, respectively, to ob- Kuriki and Fuji-Hara [18] deÿned a special class of symmetric balanced nested designs. In each of such designs, the base design (V; B) and the subdesigns (V; B i ) are an (r; )-design and (r i ; i )-designs, respectively, by recalling that i = ii .…”