-- Mathlib/Analysis/Convex/Measure.lean
theorem addHaar_frontier (hs : Convex ℝ s) : μ (frontier s) = 0

Proof state:
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
H : ∀ (t : Set E), Convex ℝ t → x ∈ interior t → Bornology.IsBounded t → μ (frontier t) = 0
B : ℕ → Set E := fun n => ball x (↑n + 1)
⊢ μ (frontier s) = 0

Tactic:
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)⟩

Result:
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
H : ∀ (t : Set E), Convex ℝ t → x ∈ interior t → Bornology.IsBounded t → μ (frontier t) = 0
B : ℕ → Set E := fun n => ball x (↑n + 1)
this : μ (⋃ n, frontier (s ∩ B n)) = 0
⊢ μ (frontier s) = 0

Proof state:
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) ≠ ⊤
this : μ (closure s) ≤ μ (interior s)
⊢ μ (frontier s) = 0

Tactic:
rwa [frontier, measure_diff interior_subset_closure isOpen_interior.nullMeasurableSet hb,
  tsub_eq_zero_iff_le]

Result:
no goals

Proof state:
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

Tactic:
refine measure_mono_null ?_ (addHaar_affineSubspace _ _ hspan)

Result:
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 ≠ ⊤
⊢ frontier s ⊆ ↑(affineSpan ℝ s)

Proof state:
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 (((ENNReal.continuous_mul_const hb).comp
  (ENNReal.continuous_coe.comp (continuous_pow d))).tendsto' _ _ ?_).mono_left nhdsWithin_le_nhds

Result:
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)

Proof state:
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:
refine ge_of_tendsto ?_ this

Result:
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)))

Proof state:
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:
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]

Result:
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)

Proof state:
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:
suffices μ (closure s) ≤ μ (interior s) by
  rwa [frontier, measure_diff interior_subset_closure isOpen_interior.nullMeasurableSet hb,
    tsub_eq_zero_iff_le]

Result:
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)