On Pseudo-automorphisms and Fusions of an Association Scheme

Abstract

wA pseudo-automorphism of an association scheme is an automorphism of its adjacency algebra with respect to both ordinary and Hadamard multiplications. An association scheme is said to be of G-type if it admits a group G of pseudo-automorphisms acting regularly on the set of adjacency matrices that are not the identity matrix. It is shown that an association scheme of G-type is amorphous if G is an elementary abelian 2-group.