Hint Resolve joinl_hom1.

(* Specifications: *)
Lemma joinl_swap n (a b: vect n) l:
cbl _ (base n 1) a ->  cbl _ (base n 1) b ->
joinl _ (a::b::l) = (-(1)).* joinl _ (b::a::l).
Lemma joinl_top n (a: vect n) l1 l2 :
(forall i, In i (a :: l1) -> cbl _ (base n 1) i) ->
joinl _ (l1 ++ (a::l2)) = (-(1))^length l1 .* joinl _ (a:: (l1 ++ l2)%list).
Lemma joinl_all n : 0 < n -> joinl n (base n 1) = E.
Definition is_vector n v := cbl _ (base n 1) v.