proposition: Lemma group_set_bigcap : group_set (\bigcap_(i | P i) F i).
proof: Proof. by elim/big_rec: _ => [|i G _ gG]; rewrite -1?(insubdK 1%G gG) groupP. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)