A class of unitary block designs

Abstract

A unital is a 2 ( q 3 + l , q + l , 1) design. Apart from the unitals associated with the unitary polarities of desarguesian planes of order q2, there is one other known family, namely those of Ree type, discovered by Liineburg [4]. Both of these families have doubly-transitive automorphism groups, and the two families are known to be distinct (see O'Nan [5]). In [2], the following result was proved: