Hello Dr.Brendan, I have got a problem. Does nauty only give us the set of generators of automorphism ? Or is there some problem with the program GAUTT ? When I try 0 1 0 1 1 0 1 0 0 1 0 1 1 0 1 0 It gives me: (1 3) (0 1)(2 3) Obviously, it ignores (0 2). Hope to hear from you! Thanks! Senlin