lean2/tests/lean/run/ftree_brec.lean

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import data.unit data.prod
inductive ftree (A : Type) (B : Type) : Type :=
leafa : ftree A B,
node : (A → B → ftree A B) → (B → ftree A B) → ftree A B
set_option pp.universes true
check @ftree
namespace ftree
namespace manual
definition below.{l l₁ l₂} {A : Type.{l₁}} {B : Type.{l₂}} (C : ftree A B → Type.{l+1}) (t : ftree A B)
: Type.{max l₁ l₂ (l+1)} :=
@rec.{(max l₁ l₂ (l+1))+1 l₁ l₂}
A
B
(λ t : ftree A B, Type.{max l₁ l₂ (l+1)})
unit.{max l₁ l₂ (l+1)}
(λ (f₁ : A → B → ftree A B)
(f₂ : B → ftree A B)
(r₁ : Π (a : A) (b : B), Type.{max l₁ l₂ (l+1)})
(r₂ : Π (b : B), Type.{max l₁ l₂ (l+1)}),
let fc₁ : Type.{max l₁ l₂ (l+1)} := Π (a : A) (b : B), C (f₁ a b) in
let fc₂ : Type.{max l₂ l+1} := Π (b : B), C (f₂ b) in
let fr₁ : Type.{max l₁ l₂ (l+1)} := Π (a : A) (b : B), r₁ a b in
let fr₂ : Type.{max l₁ l₂ (l+1)} := Π (b : B), r₂ b in
let p₁ : Type.{max l₁ l₂ (l+1)} := prod.{(max l₁ l₂ (l+1)) (max l₁ l₂ (l+1))} fc₁ fr₁ in
let p₂ : Type.{max l₁ l₂ (l+1)} := prod.{(max l₂ (l+1)) (max l₁ l₂ (l+1))} fc₂ fr₂ in
prod.{(max l₁ l₂ (l+1)) (max l₁ l₂ (l+1))} p₁ p₂)
t
definition pbelow.{l₁ l₂} {A : Type.{l₁}} {B : Type.{l₂}} (C : ftree A B → Prop) (t : ftree A B)
: Prop :=
@rec.{1 l₁ l₂}
A
B
(λ t : ftree A B, Prop)
true
(λ (f₁ : A → B → ftree A B)
(f₂ : B → ftree A B)
(r₁ : Π (a : A) (b : B), Prop)
(r₂ : Π (b : B), Prop),
let fc₁ : Prop := ∀ (a : A) (b : B), C (f₁ a b) in
let fc₂ : Prop := ∀ (b : B), C (f₂ b) in
let fr₁ : Prop := ∀ (a : A) (b : B), r₁ a b in
let fr₂ : Prop := ∀ (b : B), r₂ b in
let p₁ : Prop := fc₁ ∧ fr₁ in
let p₂ : Prop := fc₂ ∧ fr₂ in
p₁ ∧ p₂)
t
definition brec_on.{l l₁ l₂} {A : Type.{l₁}} {B : Type.{l₂}} {C : ftree A B → Type.{l+1}}
(t : ftree A B)
(F : Π (t : ftree A B), @below A B C t → C t)
: C t :=
have gen : prod.{(l+1) (max l₁ l₂ (l+1))} (C t) (@below A B C t), from
@rec.{(max l₁ l₂ (l+1)) l₁ l₂}
A
B
(λ t : ftree A B, prod.{(l+1) (max l₁ l₂ (l+1))} (C t) (@below A B C t))
(have b : @below A B C (leafa A B), from
unit.star.{max l₁ l₂ (l+1)},
have c : C (leafa A B), from
F (leafa A B) b,
prod.mk.{(l+1) (max l₁ l₂ (l+1))} c b)
(λ (f₁ : A → B → ftree A B)
(f₂ : B → ftree A B)
(r₁ : Π (a : A) (b : B), prod.{(l+1) (max l₁ l₂ (l+1))} (C (f₁ a b)) (@below A B C (f₁ a b)))
(r₂ : Π (b : B), prod.{(l+1) (max l₁ l₂ (l+1))} (C (f₂ b)) (@below A B C (f₂ b))),
let fc₁ : Π (a : A) (b : B), C (f₁ a b) := λ (a : A) (b : B), prod.pr1 (r₁ a b) in
let fr₁ : Π (a : A) (b : B), @below A B C (f₁ a b) := λ (a : A) (b : B), prod.pr2 (r₁ a b) in
let fc₂ : Π (b : B), C (f₂ b) := λ (b : B), prod.pr1 (r₂ b) in
let fr₂ : Π (b : B), @below A B C (f₂ b) := λ (b : B), prod.pr2 (r₂ b) in
have b : @below A B C (node f₁ f₂), from
prod.mk (prod.mk fc₁ fr₁) (prod.mk fc₂ fr₂),
have c : C (node f₁ f₂), from
F (node f₁ f₂) b,
prod.mk c b)
t,
prod.pr1 gen
definition binduction_on.{l₁ l₂} {A : Type.{l₁}} {B : Type.{l₂}} {C : ftree A B → Prop}
(t : ftree A B)
(F : Π (t : ftree A B), @ibelow A B C t → C t)
: C t :=
have gen : C t ∧ @ibelow A B C t, from
@rec.{0 l₁ l₂}
A
B
(λ t : ftree A B, C t ∧ @ibelow A B C t)
(have b : @ibelow A B C (leafa A B), from
true.intro,
have c : C (leafa A B), from
F (leafa A B) b,
and.intro c b)
(λ (f₁ : A → B → ftree A B)
(f₂ : B → ftree A B)
(r₁ : ∀ (a : A) (b : B), C (f₁ a b) ∧ @ibelow A B C (f₁ a b))
(r₂ : ∀ (b : B), C (f₂ b) ∧ @ibelow A B C (f₂ b)),
let fc₁ : ∀ (a : A) (b : B), C (f₁ a b) := λ (a : A) (b : B), and.elim_left (r₁ a b) in
let fr₁ : ∀ (a : A) (b : B), @ibelow A B C (f₁ a b) := λ (a : A) (b : B), and.elim_right (r₁ a b) in
let fc₂ : ∀ (b : B), C (f₂ b) := λ (b : B), and.elim_left (r₂ b) in
let fr₂ : ∀ (b : B), @ibelow A B C (f₂ b) := λ (b : B), and.elim_right (r₂ b) in
have b : @ibelow A B C (node f₁ f₂), from
and.intro (and.intro fc₁ fr₁) (and.intro fc₂ fr₂),
have c : C (node f₁ f₂), from
F (node f₁ f₂) b,
and.intro c b)
t,
and.elim_left gen
end manual
end ftree