proposition: Lemma afix_cycle_in a : a \in D -> 'Fix_to(<[a]>) = 'Fix_to[a].
proof: Proof. by move=> Da; rewrite afix_gen_in ?sub1set. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)