fact: Fixpoint Adds {A:Type}(X: Ensemble A)(l: list A) := match l with nil => X | x::l => Add (Adds X l) x end.
imports: Coq(Arith Lists.List) hydras.Ackermann(fol folProp folProof Languages folLogic folLogic2 folLogic3 subAll Deduction primRec)