-- Mathlib/MeasureTheory/Measure/Haar/Basic.lean
theorem chaar_self (K₀ : PositiveCompacts G) : chaar K₀ K₀.toCompacts = 1

Proof state:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
⊢ chaar K₀ K₀.toCompacts = 1

Tactic:
have : Continuous eval := continuous_apply _

Result:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ chaar K₀ K₀.toCompacts = 1

Proof state:
case intro.intro.intro.intro
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
U : Set G
left✝ : U ⊆ ↑⊤.toOpens
h2U : IsOpen U
h3U : 1 ∈ U
⊢ prehaar (↑K₀) U ∈ eval ⁻¹' {1}

Tactic:
apply prehaar_self

Result:
case intro.intro.intro.intro.hU
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
U : Set G
left✝ : U ⊆ ↑⊤.toOpens
h2U : IsOpen U
h3U : 1 ∈ U
⊢ (interior U).Nonempty

Proof state:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ closure (prehaar ↑K₀ '' {U | U ⊆ ↑⊤.toOpens ∧ IsOpen U ∧ 1 ∈ U}) ⊆ eval ⁻¹' {1}

Tactic:
rw [IsClosed.closure_subset_iff]

Result:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ prehaar ↑K₀ '' {U | U ⊆ ↑⊤.toOpens ∧ IsOpen U ∧ 1 ∈ U} ⊆ eval ⁻¹' {1}

G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ IsClosed (eval ⁻¹' {1})

Proof state:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
⊢ chaar K₀ K₀.toCompacts = 1

Tactic:
let eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts

Result:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
⊢ chaar K₀ K₀.toCompacts = 1

Proof state:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ clPrehaar ↑K₀ ⊤ ⊆ eval ⁻¹' {1}

Tactic:
unfold clPrehaar

Result:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ closure (prehaar ↑K₀ '' {U | U ⊆ ↑⊤.toOpens ∧ IsOpen U ∧ 1 ∈ U}) ⊆ eval ⁻¹' {1}

Proof state:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ chaar K₀ ∈ eval ⁻¹' {1}

Tactic:
apply mem_of_subset_of_mem _ (chaar_mem_clPrehaar K₀ ⊤)

Result:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ clPrehaar ↑K₀ ⊤ ⊆ eval ⁻¹' {1}

Proof state:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ chaar K₀ K₀.toCompacts = 1

Tactic:
show chaar K₀ ∈ eval ⁻¹' {(1 : ℝ)}

Result:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ chaar K₀ ∈ eval ⁻¹' {1}

Proof state:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ prehaar ↑K₀ '' {U | U ⊆ ↑⊤.toOpens ∧ IsOpen U ∧ 1 ∈ U} ⊆ eval ⁻¹' {1}

Tactic:
rintro _ ⟨U, ⟨_, h2U, h3U⟩, rfl⟩

Result:
case intro.intro.intro.intro
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
U : Set G
left✝ : U ⊆ ↑⊤.toOpens
h2U : IsOpen U
h3U : 1 ∈ U
⊢ prehaar (↑K₀) U ∈ eval ⁻¹' {1}

Proof state:
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ IsClosed (eval ⁻¹' {1})

Tactic:
apply continuous_iff_isClosed.mp this

Result:
case a
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ IsClosed {1}

Proof state:
case intro.intro.intro.intro.hU
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
U : Set G
left✝ : U ⊆ ↑⊤.toOpens
h2U : IsOpen U
h3U : 1 ∈ U
⊢ (interior U).Nonempty

Tactic:
rw [h2U.interior_eq]

Result:
case intro.intro.intro.intro.hU
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
U : Set G
left✝ : U ⊆ ↑⊤.toOpens
h2U : IsOpen U
h3U : 1 ∈ U
⊢ U.Nonempty

Proof state:
case a
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
⊢ IsClosed {1}

Tactic:
exact isClosed_singleton

Result:
no goals

Proof state:
case intro.intro.intro.intro.hU
G : Type u_1
inst✝² : Group G
inst✝¹ : TopologicalSpace G
inst✝ : IsTopologicalGroup G
K₀ : PositiveCompacts G
eval : (Compacts G → ℝ) → ℝ := fun f => f K₀.toCompacts
this : Continuous eval
U : Set G
left✝ : U ⊆ ↑⊤.toOpens
h2U : IsOpen U
h3U : 1 ∈ U
⊢ U.Nonempty

Tactic:
exact ⟨1, h3U⟩

Result:
no goals