proposition: Lemma astabs1 : 'N(1 | to) = D.
proof: Proof. by rewrite astabs_set1 astab1. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat div seq) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient)