fact: Fixpoint dom (C : Type) (E : list (X.t*C)) : KeySet.t := match E with | nil => empty | (x, _) :: E' => add x (dom E') end.
imports: Coq.FSets.FSets Coq.Lists.List Coq.Logic.Decidable Coq.Strings.String String Metalib.CoqFSetDecide Metalib.CoqListFacts Metalib.LibTactics Metalib.CoqFSetInterface Coq.Classes.Equivalence Coq.Classes.EquivDec Metalib.CoqEqDec