Definition Infinite_ok (A:Type) (X:LList A -> Prop) :=
forall l:LList A,
X l -> exists a : A | ( exists l' : LList A | l = LCons a l' /\ X l').
Definition Infinite1 (A:Type) (l:LList A) :=
exists X : LList A -> Prop | Infinite_ok X /\ X l.