Some work to report here is on computer searches for BIBDs with cyclic or 1-rotational automorphism groups and some more general groups, including info on the block intersection patterns.
Constructions based on geometries are standard, but I have tried to generalise the constructions of GDDs from these here. This is based on work by M.Greig and Carmichael. I cannot guarantee that it is original, but I am not aware of such results elsewhere: my apologies if I have omitted to acknowledge someone else's work in consequence. In some respects this is an analysis of the block structure of the designs, perhaps an alternative to the block intersection patterns.
Last Updated on 20/10/2004
By D.H.Rees