Unifying some known infinite families of combinatorial 3-designs

In this paper we present a construction of 3-designs by using a 3-design with resolvability. The basic construction generalizes a well-known construction of simple 3- ( v , 4 , 3 ) designs by Jungnickel and Vanstone (1986). We investigate the conditions under which the designs obtained by the basic construction are simple. Many infinite families of simple 3-designs are presented, which are closely related to some known families by Iwasaki and Meixner (1995), Laue (2004) and van Tran (2000, 2001). On the other hand, the designs obtained by the basic construction possess various properties: A theory of constructing simple cyclic 3- ( v , 4 , 3 ) designs by Köhler (1981) can be readily rebuilt from the context of this paper. Moreover many infinite families of simple resolvable 3-designs are presented in comparison with some known families. We also show that for any prime power q and any odd integer n there exists a resolvable 3- ( q n + 1 , q + 1 , 1 ) design. As far as the authors know, this is the first and the only known infinite family of resolvable t- ( v , k , 1 ) designs with t ⩾ 3 and k ⩾ 5 . Those resolvable designs can again be used to obtain more infinite families of simple 3-designs through the basic construction.