(* The left contraction (Dorst inner product) *)
Notation "x ''L[' l ]  y " := (l_contra _ l x y) (at level 40).
Notation hom := (hom p _).

Lemma l_contra_joinl n l x y z :
(x ∧ y) 'L[l] z = x 'L[l] (y 'L[l] z) :> vect n.