[For the entire collection see Zbl 0704.00023.] A t-(v,k,$λ$) design is a pair (X,B) with a v-set X of points and a family B of K-subsets of X called blocks such that any t points are contained in exactly $λ$ blocks. The authors present technique used in the construction of two non- isomorphic simple 6-(14,7,4) designs and four non-isomorphic simple 5- (13,6,4) designs. The described methods are successful in finding some other designs. Two open problems are proposed.
Reviewer: M.Kratko