GL_' n ( p ) }") : type_scope.

Section GL_unit.

(* Specifications: *)
Proof. by move=> Ua; rewrite !uni
Qed.
Proof. by move=> A uA /= B; rewrite -mulmxA mul
Proof. by rewrite -unitrM -det_mulmx. Qed.
Proof. by rewrite (fun_if trmx)
Proof. by move=> AB1; apply/andP; rewrite -unitmx_mul AB1 unitmx1. Q