Manchester Geometry Seminar 1999/2000

In their classical works of the seventies, Arnold and Brieskorn discovered a remarkable relationship between Weyl groups and isolated singularities of holomorphic functions. I will show how certain finite groups generated by unitary reflections are similarly naturally related to functions with cyclic symmetry. The construction yields a way to obtain analogues of Dynkin diagrams for complex reflection groups by folding the ADE diagrams which generalises that of folding A_2k-1 to B_k.