(* 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_ei n l i :
i < n -> 'e_i 'L[l] 'e_i = [projk i l] :> vect n.