On meta-thin association schemes
An association scheme is a combinatorial object derived from the orbitals of a transitive permutation group. Let G be a transitive permutation group acting on a finite set X. Then   is a normal subgroup of G where G(x) :={gis an element ofG \ x(g) =x}. A meta-thin association scheme can be considered as a generalization of the situation where   normalizes G(x). In this paper, we consider the automorphism group of a meta-thin association scheme, and obtain a sufficient condition for a meta-thin association scheme to have a transitive automorphism group. This enables us to conclude that every meta-thin association scheme with its thin residue isomorphic to the cyclic group of order pq, where p and q are primes, has a transitive automorphism group.
association schemes automorphisms