(* Iterated contraction *)
Definition mcontra n (ll: list (kn n)) (x: vect n) :=
fold_left (fun x l => #<l,x>#) ll x.
Notation "#<< l , x >>#" := (mcontra _ l x).

Lemma mcontra0 n lfs : #<< lfs, 0 >># = (0: vect n).
Hint Rewrite mcontra0: GRm0.