In this section we define the predicate ``Even'', and prove some theorems characterising it.
** Module lib_nat_Even Imports lib_nat Even = ... : nat->Prop ev1 = ... : Even zero ev2 = ... : {n:nat}(Even n)->Even (suc (suc n)) Even_elim_nondep = ... : {T:nat->Prop}(T zero)->({n:nat}(T n)->T (suc (suc n)))->{n:nat} (Even n)->T n Even_inv = ... : {n:nat}(Even n)-> (Eq n zero \/ Ex ([x:nat](Eq n (suc (suc x)) /\ Even x))) Even_inv' = ... : {n:nat}(Even (suc (suc n)))->Even n