Section ListProperties.
Variable  X : Type.
Variables x y : X.
Variables l l1 l2 l3 : list X.

Lemma disjoint_cons_r :
forall A B C D x a (E : list (asn A B)) (F : list (asn C D)),
disjoint F (VarAsn _ x a :: E) <-> ~ In x (dom F) /\ disjoint E F.