fact: Axiom disjoint_one_l : forall A B (x : atom) (a : A) (E : list (atom*B)), disjoint (x ~ a) E <-> ~ In x (dom E).
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.AssocList Metalib.MetatheoryAtom Metalib.LibTactics