(* QuickChick ev_sum. *)

Inductive ev' : nat -> Prop :=
| ev'_0 : ev' 0
| ev'_2 : ev' 2
| ev'_sum : forall n m, ev' n -> ev' m -> ev' (n + m).(* QuickChick ev_sum. *)

Inductive ev' : nat -> Prop :=
| ev'_0 : ev' 0
| ev'_2 : ev' 2
| ev'_sum : forall n m, ev' n -> ev' m -> ev' (n + m).(* QuickChick ev_sum. *)

Inductive ev' : nat -> Prop :=
| ev'_0 : ev' 0
| ev'_2 : ev' 2
| ev'_sum : forall n m, ev' n -> ev' m -> ev' (n + m).(* QuickChick ev_sum. *)

Inductive ev' : nat -> Prop :=
| ev'_0 : ev' 0
| ev'_2 : ev' 2
| ev'_sum : forall n m, ev' n -> ev' m -> ev' (n + m).

(* Specifications: *)
Theorem ev'_ev : forall n, ev' n <-> ev n.
Theorem ev_ev__ev : forall n m, ev (n+m) -> ev n -> ev m.
Theorem ev_plus_plus : forall n m p, ev (n+m) -> ev (n+p) -> ev (m+p).