proposition: Fact fixedField_is_aspace E (A : {set gal_of E}) : is_aspace (fixedField A).
proof: Proof. rewrite /fixedField; elim/big_rec: _ {1}E => [|x K _ IH_K] M. exact: (valP (M :&: _)%AS). by rewrite capvA IH_K. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(choice fintype tuple finfun bigop ssralg poly) mathcomp(polydiv finset fingroup morphism quotient perm) mathcomp(action zmodp cyclic matrix mxalgebra vector) mathcomp(falgebra fieldext separable)