Large Sets of t-Designs from Groups
Resolutions of t-designs were studied as early as 1847 by Reverend T. P. Kirkman who proposed the famous 15 schoolgirls problem. A large set of t−(v,k,λ) designs is a partition of the complete design (Xk) into block-disjoint t−(v,k,λ) designs. We discuss prolific families of semiregular large sets of 2-designs and 3-designs arising from the 2-homogeneous half-affine groups acting on q=pa points, and the 3-homogeneous PSL2(q) acting on the projective line. Time permitting, we discuss orthogonality of large sets, present the entertaining Kramer's 7×7×7 Steiner cube, and offer some tantalizing open problems.
This is joint work with Chuck Cusack, Michael Hurley and Oscar Lopez.
Bio: Spyros is Professor Emeritus in the Department of Mathematical Sciences at Florida Atlantic University. With a Ph.D. from Birmingham, his interests lie at the intersection of nite group theory, combinatorial design theory, and cryptography. Spyros is a fan of good food, good friends and good theorems.