proposition: Lemma commG1 A : [~: A, 1] = 1.
proof: Proof. by apply/commG1P; rewrite centsC sub1G. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat fintype) mathcomp(bigop finset binomial fingroup morphism) mathcomp(automorphism quotient gfunctor)