> %default total > %access public export > %auto_implicits off > Natural : {F, G : Type -> Type} -> > (Functor F) => (Functor G) => > (t : {A : Type} -> F A -> G A) -> > Type > Natural {F} {G} t = {A, B : Type} -> > (f : A -> B) -> > (x : F A) -> > t (map f x) = map f (t x) > Monotone : {B, C : Type} -> {F : Type -> Type} -> (Functor F) => > (LTE_B : B -> B -> Type) -> > (LTE_C : C -> C -> Type) -> > (measure : F B -> C) -> > Type > Monotone {B} {C} {F} LTE_B LTE_C measure = > {A : Type} -> > (f : A -> B) -> > (g : A -> B) -> > (p : (a : A) -> f a `LTE_B` g a) -> > (x : F A) -> > measure (map f x) `LTE_C` measure (map g x) > monotoneNaturalLemma: {B, C : Type} -> {F : Type -> Type} -> (Functor F) => > (LTE_B : B -> B -> Type) -> > (LTE_C : C -> C -> Type) -> > (measure : F B -> C) -> > Monotone LTE_B LTE_C measure -> > (t : {A : Type} -> F A -> F A) -> > Natural t -> > Monotone LTE_B LTE_C (measure . t) > monotoneNaturalLemma {B} {C} {F} LTE_B LTE_C m mm t nt = mmt where > mmt : {A : Type} -> > (f : A -> B) -> > (g : A -> B) -> > (p : (a : A) -> f a `LTE_B` g a) -> > (x : F A) -> > m (t {A = B} (map f x)) `LTE_C` m (t {A = B} (map g x)) > mmt = ?kika