Theorem: Convex.addHaar_frontier
File: Mathlib/Analysis/Convex/Measure.lean

Proof steps:
state_before: E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
⊢ μ (frontier s) = 0
state_after: case inl
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
hspan : affineSpan ℝ s ≠ ⊤
⊢ μ (frontier s) = 0

case inr
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
hspan : affineSpan ℝ s = ⊤
⊢ μ (frontier s) = 0
tactic: cases' ne_or_eq (affineSpan ℝ s) ⊤ with hspan hspan
state_before: case inr
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
hspan : affineSpan ℝ s = ⊤
⊢ μ (frontier s) = 0
state_after: case inr
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
hspan : (interior s).Nonempty
⊢ μ (frontier s) = 0
tactic: rw [← hs.interior_nonempty_iff_affineSpan_eq_top] at hspan
state_before: case inr
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
hspan : (interior s).Nonempty
⊢ μ (frontier s) = 0
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
x : E
hx : x ∈ interior s
⊢ μ (frontier s) = 0
tactic: rcases hspan with ⟨x, hx⟩
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
x : E
hx : x ∈ interior s
⊢ μ (frontier s) = 0
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
x : E
hx : x ∈ interior s
⊢ ∀ (t : Set E), Convex ℝ t → x ∈ interior t → Bornology.IsBounded t → μ (frontier t) = 0
tactic: suffices H : ∀ t : Set E, Convex ℝ t → x ∈ interior t → IsBounded t → μ (frontier t) = 0 by
    let B : ℕ → Set E := fun n => ball x (n + 1)
    have : μ (⋃ n : ℕ, frontier (s ∩ B n)) = 0 := by
      refine measure_iUnion_null fun n =>
        H _ (hs.inter (convex_ball _ _)) ?_ (isBounded_ball.subset inter_subset_right)
      rw [interior_inter, isOpen_ball.interior_eq]
      exact ⟨hx, mem_ball_self (add_pos_of_nonneg_of_pos n.cast_nonneg zero_lt_one)⟩
    refine measure_mono_null (fun y hy => ?_) this; clear this
    set N : ℕ := ⌊dist y x⌋₊
    refine mem_iUnion.2 ⟨N, ?_⟩
    have hN : y ∈ B N := by simp [B, N, Nat.lt_floor_add_one]
    suffices y ∈ frontier (s ∩ B N) ∩ B N from this.1
    rw [frontier_inter_open_inter isOpen_ball]
    exact ⟨hy, hN⟩
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s : Set E
hs : Convex ℝ s
x : E
hx : x ∈ interior s
⊢ ∀ (t : Set E), Convex ℝ t → x ∈ interior t → Bornology.IsBounded t → μ (frontier t) = 0
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : Bornology.IsBounded s
⊢ μ (frontier s) = 0
tactic: intro s hs hx hb
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : Bornology.IsBounded s
⊢ μ (frontier s) = 0
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
⊢ μ (frontier s) = 0
tactic: replace hb : μ (interior s) ≠ ∞ := (hb.subset interior_subset).measure_lt_top.ne
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
⊢ μ (frontier s) = 0
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
⊢ μ (closure s) ≤ μ (interior s)
tactic: suffices μ (closure s) ≤ μ (interior s) by
    rwa [frontier, measure_diff interior_subset_closure isOpen_interior.measurableSet hb,
      tsub_eq_zero_iff_le]
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
⊢ μ (closure s) ≤ μ (interior s)
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
⊢ μ (closure s) ≤ μ (interior s)
tactic: set d : ℕ := FiniteDimensional.finrank ℝ E
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
⊢ μ (closure s) ≤ μ (interior s)
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
this : ∀ (r : ℝ≥0), 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
⊢ μ (closure s) ≤ μ (interior s)
tactic: have : ∀ r : ℝ≥0, 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s) := fun r hr ↦ by
    refine (measure_mono <|
      hs.closure_subset_image_homothety_interior_of_one_lt hx r hr).trans_eq ?_
    rw [addHaar_image_homothety, ← NNReal.coe_pow, NNReal.abs_eq, ENNReal.ofReal_coe_nnreal]
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
this : ∀ (r : ℝ≥0), 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
⊢ μ (closure s) ≤ μ (interior s)
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
this✝ : ∀ (r : ℝ≥0), 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
this : ∀ᶠ (r : ℝ≥0) in 𝓝[>] 1, μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
⊢ μ (closure s) ≤ μ (interior s)
tactic: have : ∀ᶠ (r : ℝ≥0) in 𝓝[>] 1, μ (closure s) ≤ ↑(r ^ d) * μ (interior s) :=
    mem_of_superset self_mem_nhdsWithin this
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
this✝ : ∀ (r : ℝ≥0), 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
this : ∀ᶠ (r : ℝ≥0) in 𝓝[>] 1, μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
⊢ μ (closure s) ≤ μ (interior s)
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
this✝ : ∀ (r : ℝ≥0), 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
this : ∀ᶠ (r : ℝ≥0) in 𝓝[>] 1, μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
⊢ Tendsto (fun c => ↑(c ^ d) * μ (interior s)) (𝓝[>] 1) (𝓝 (μ (interior s)))
tactic: refine ge_of_tendsto ?_ this
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
this✝ : ∀ (r : ℝ≥0), 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
this : ∀ᶠ (r : ℝ≥0) in 𝓝[>] 1, μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
⊢ Tendsto (fun c => ↑(c ^ d) * μ (interior s)) (𝓝[>] 1) (𝓝 (μ (interior s)))
state_after: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
this✝ : ∀ (r : ℝ≥0), 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
this : ∀ᶠ (r : ℝ≥0) in 𝓝[>] 1, μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
⊢ ((fun x => x * μ (interior s)) ∘ ENNReal.ofNNReal ∘ fun a => a ^ d) 1 = μ (interior s)
tactic: refine (((ENNReal.continuous_mul_const hb).comp
    (ENNReal.continuous_coe.comp (continuous_pow d))).tendsto' _ _ ?_).mono_left nhdsWithin_le_nhds
state_before: case inr.intro
E : Type u_1
inst✝⁵ : NormedAddCommGroup E
inst✝⁴ : NormedSpace ℝ E
inst✝³ : MeasurableSpace E
inst✝² : BorelSpace E
inst✝¹ : FiniteDimensional ℝ E
μ : Measure E
inst✝ : μ.IsAddHaarMeasure
s✝ : Set E
hs✝ : Convex ℝ s✝
x : E
hx✝ : x ∈ interior s✝
s : Set E
hs : Convex ℝ s
hx : x ∈ interior s
hb : μ (interior s) ≠ ⊤
d : ℕ := finrank ℝ E
this✝ : ∀ (r : ℝ≥0), 1 < r → μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
this : ∀ᶠ (r : ℝ≥0) in 𝓝[>] 1, μ (closure s) ≤ ↑(r ^ d) * μ (interior s)
⊢ ((fun x => x * μ (interior s)) ∘ ENNReal.ofNNReal ∘ fun a => a ^ d) 1 = μ (interior s)
state_after: no goals
tactic: simp