Theorem: ENNReal.liminf_toReal_eq
File: Mathlib/Topology/Instances/ENNReal.lean

Proof steps:
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
⊢ liminf (fun i => (xs i).toReal) F = (liminf xs F).toReal
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
⊢ liminf (fun i => (xs i).toReal) F = (liminf xs F).toReal
tactic: have liminf_le : F.liminf xs ≤ b := by
    apply liminf_le_of_le ⟨0, by simp⟩
    intro y h
    obtain ⟨i, hi⟩ := (Eventually.and h le_b).exists
    exact hi.1.trans hi.2
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
⊢ liminf (fun i => (xs i).toReal) F = (liminf xs F).toReal
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
⊢ liminf (fun i => (xs i).toReal) F = (liminf xs F).toReal
tactic: have aux : ∀ᶠ i in F, (xs i).toReal = ENNReal.truncateToReal b (xs i) := by
    filter_upwards [le_b] with i i_le_b
    simp only [truncateToReal_eq_toReal b_ne_top i_le_b, implies_true]
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
⊢ liminf (fun i => (xs i).toReal) F = (liminf xs F).toReal
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
aux' : (liminf xs F).toReal = b.truncateToReal (liminf xs F)
⊢ liminf (fun i => (xs i).toReal) F = (liminf xs F).toReal
tactic: have aux' : (F.liminf xs).toReal = ENNReal.truncateToReal b (F.liminf xs) := by
    rw [truncateToReal_eq_toReal b_ne_top liminf_le]
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
aux' : (liminf xs F).toReal = b.truncateToReal (liminf xs F)
⊢ liminf (fun i => (xs i).toReal) F = (liminf xs F).toReal
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
aux' : (liminf xs F).toReal = b.truncateToReal (liminf xs F)
⊢ liminf (fun a => b.truncateToReal (xs a)) F = b.truncateToReal (liminf xs F)
tactic: simp_rw [liminf_congr aux, aux']
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
aux' : (liminf xs F).toReal = b.truncateToReal (liminf xs F)
⊢ liminf (fun a => b.truncateToReal (xs a)) F = b.truncateToReal (liminf xs F)
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
aux' : (liminf xs F).toReal = b.truncateToReal (liminf xs F)
key : b.truncateToReal (liminf xs F) = liminf (b.truncateToReal ∘ xs) F
⊢ liminf (fun a => b.truncateToReal (xs a)) F = b.truncateToReal (liminf xs F)
tactic: have key := Monotone.map_liminf_of_continuousAt (F := F) (monotone_truncateToReal b_ne_top) xs
          (continuous_truncateToReal b_ne_top).continuousAt
          (IsBoundedUnder.isCoboundedUnder_ge ⟨b, by simpa only [eventually_map] using le_b⟩)
          ⟨0, eventually_of_forall (by simp)⟩
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
aux' : (liminf xs F).toReal = b.truncateToReal (liminf xs F)
key : b.truncateToReal (liminf xs F) = liminf (b.truncateToReal ∘ xs) F
⊢ liminf (fun a => b.truncateToReal (xs a)) F = b.truncateToReal (liminf xs F)
state_after: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
aux' : (liminf xs F).toReal = b.truncateToReal (liminf xs F)
key : b.truncateToReal (liminf xs F) = liminf (b.truncateToReal ∘ xs) F
⊢ liminf (fun a => b.truncateToReal (xs a)) F = liminf (b.truncateToReal ∘ xs) F
tactic: rw [key]
state_before: α : Type u_1
β : Type u_2
γ : Type u_3
ι✝ : Type u_4
ι : Type u_5
F : Filter ι
inst✝ : F.NeBot
b : ℝ≥0∞
b_ne_top : b ≠ ⊤
xs : ι → ℝ≥0∞
le_b : ∀ᶠ (i : ι) in F, xs i ≤ b
liminf_le : liminf xs F ≤ b
aux : ∀ᶠ (i : ι) in F, (xs i).toReal = b.truncateToReal (xs i)
aux' : (liminf xs F).toReal = b.truncateToReal (liminf xs F)
key : b.truncateToReal (liminf xs F) = liminf (b.truncateToReal ∘ xs) F
⊢ liminf (fun a => b.truncateToReal (xs a)) F = liminf (b.truncateToReal ∘ xs) F
state_after: no goals
tactic: rfl