Theorem: ContinuousMap.idealOfSet_ofIdeal_eq_closure
File: Mathlib/Topology/ContinuousFunction/Ideals.lean

Proof steps:
state_before: X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
⊢ idealOfSet 𝕜 (setOfIdeal I) = I.closure
state_after: X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
⊢ idealOfSet 𝕜 (setOfIdeal I) ≤ I.closure
tactic: refine le_antisymm ?_
      ((idealOfSet_closed 𝕜 <| setOfIdeal I).closure_subset_iff.mpr fun f hf x hx =>
        not_mem_setOfIdeal.mp hx hf)
state_before: X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
⊢ idealOfSet 𝕜 (setOfIdeal I) ≤ I.closure
state_after: X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ
hε : ε > 0
⊢ ∃ b ∈ ↑I, dist f b < ε
tactic: refine (fun f hf => Metric.mem_closure_iff.mpr fun ε hε => ?_)
state_before: X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ
hε : ε > 0
⊢ ∃ b ∈ ↑I, dist f b < ε
state_after: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : ↑ε > 0
⊢ ∃ b ∈ ↑I, dist f b < ↑ε
tactic: lift ε to ℝ≥0 using hε.lt.le
state_before: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : ↑ε > 0
⊢ ∃ b ∈ ↑I, dist f b < ↑ε
state_after: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
⊢ ∃ b ∈ ↑I, dist f b < ↑ε
tactic: replace hε := show (0 : ℝ≥0) < ε from hε
state_before: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
⊢ ∃ b ∈ ↑I, dist f b < ↑ε
state_after: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
⊢ ∃ b ∈ ↑I, ↑(nndist f b) < ↑ε
tactic: simp_rw [dist_nndist]
state_before: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
⊢ ∃ b ∈ ↑I, ↑(nndist f b) < ↑ε
state_after: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
⊢ ∃ b ∈ ↑I, nndist f b < ε
tactic: norm_cast
state_before: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
⊢ ∃ b ∈ ↑I, nndist f b < ε
state_after: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
⊢ ∃ b ∈ ↑I, nndist f b < ε
tactic: set t := {x : X | ε / 2 ≤ ‖f x‖₊}
state_before: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
⊢ ∃ b ∈ ↑I, nndist f b < ε
state_after: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
⊢ ∃ b ∈ ↑I, nndist f b < ε
tactic: have ht : IsClosed t := isClosed_le continuous_const (map_continuous f).nnnorm
state_before: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
⊢ ∃ b ∈ ↑I, nndist f b < ε
state_after: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
⊢ ∃ b ∈ ↑I, nndist f b < ε
tactic: have htI : Disjoint t (setOfIdeal I)ᶜ := by
    refine Set.subset_compl_iff_disjoint_left.mp fun x hx => ?_
    simpa only [t, Set.mem_setOf, Set.mem_compl_iff, not_le] using
      (nnnorm_eq_zero.mpr (mem_idealOfSet.mp hf hx)).trans_lt (half_pos hε)
state_before: case intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
this : ∃ g', (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I ∧ ∀ x ∈ t, 0 < g' x
⊢ ∃ g, (↑(algebraMapCLM ℝ≥0 𝕜)).comp g ∈ I ∧ (∀ (x : X), g x ≤ 1) ∧ Set.EqOn (⇑g) 1 t
state_after: case intro.intro.intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
⊢ ∃ g, (↑(algebraMapCLM ℝ≥0 𝕜)).comp g ∈ I ∧ (∀ (x : X), g x ≤ 1) ∧ Set.EqOn (⇑g) 1 t
tactic: obtain ⟨g', hI', hgt'⟩ := this
state_before: case intro.intro.intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
⊢ ∃ g, (↑(algebraMapCLM ℝ≥0 𝕜)).comp g ∈ I ∧ (∀ (x : X), g x ≤ 1) ∧ Set.EqOn (⇑g) 1 t
state_after: case intro.intro.intro.intro.intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
⊢ ∃ g, (↑(algebraMapCLM ℝ≥0 𝕜)).comp g ∈ I ∧ (∀ (x : X), g x ≤ 1) ∧ Set.EqOn (⇑g) 1 t
tactic: obtain ⟨c, hc, hgc'⟩ : ∃ c > 0, ∀ y : X, y ∈ t → c ≤ g' y :=
    t.eq_empty_or_nonempty.elim
      (fun ht' => ⟨1, zero_lt_one, fun y hy => False.elim (by rwa [ht'] at hy)⟩) fun ht' =>
      let ⟨x, hx, hx'⟩ := ht.isCompact.exists_isMinOn ht' (map_continuous g').continuousOn
      ⟨g' x, hgt' x hx, hx'⟩
state_before: case intro.intro.intro.intro.intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
⊢ ∃ g, (↑(algebraMapCLM ℝ≥0 𝕜)).comp g ∈ I ∧ (∀ (x : X), g x ≤ 1) ∧ Set.EqOn (⇑g) 1 t
state_after: case intro.intro.intro.intro.intro.intro.intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
g : C(X, ℝ≥0)
hg : ∀ (x : X), (g * g') x ≤ 1
hgc : Set.EqOn (⇑(g * g')) 1 {x | c ≤ g' x}
⊢ ∃ g, (↑(algebraMapCLM ℝ≥0 𝕜)).comp g ∈ I ∧ (∀ (x : X), g x ≤ 1) ∧ Set.EqOn (⇑g) 1 t
tactic: obtain ⟨g, hg, hgc⟩ := exists_mul_le_one_eqOn_ge g' hc
state_before: case intro.intro.intro.intro.intro.intro.intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
g : C(X, ℝ≥0)
hg : ∀ (x : X), (g * g') x ≤ 1
hgc : Set.EqOn (⇑(g * g')) 1 {x | c ≤ g' x}
⊢ ∃ g, (↑(algebraMapCLM ℝ≥0 𝕜)).comp g ∈ I ∧ (∀ (x : X), g x ≤ 1) ∧ Set.EqOn (⇑g) 1 t
state_after: case intro.intro.intro.intro.intro.intro.intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
g : C(X, ℝ≥0)
hg : ∀ (x : X), (g * g') x ≤ 1
hgc : Set.EqOn (⇑(g * g')) 1 {x | c ≤ g' x}
⊢ (↑(algebraMapCLM ℝ≥0 𝕜)).comp (g * g') ∈ I
tactic: refine ⟨g * g', ?_, hg, hgc.mono hgc'⟩
state_before: case intro.intro.intro.intro.intro.intro.intro
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
g : C(X, ℝ≥0)
hg : ∀ (x : X), (g * g') x ≤ 1
hgc : Set.EqOn (⇑(g * g')) 1 {x | c ≤ g' x}
⊢ (↑(algebraMapCLM ℝ≥0 𝕜)).comp (g * g') ∈ I
state_after: case h.e'_4
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
g : C(X, ℝ≥0)
hg : ∀ (x : X), (g * g') x ≤ 1
hgc : Set.EqOn (⇑(g * g')) 1 {x | c ≤ g' x}
⊢ (↑(algebraMapCLM ℝ≥0 𝕜)).comp (g * g') = (↑(algebraMapCLM ℝ≥0 𝕜)).comp g * (↑(algebraMapCLM ℝ≥0 𝕜)).comp g'
tactic: convert I.mul_mem_left ((algebraMapCLM ℝ≥0 𝕜 : C(ℝ≥0, 𝕜)).comp g) hI'
state_before: case h.e'_4
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
g : C(X, ℝ≥0)
hg : ∀ (x : X), (g * g') x ≤ 1
hgc : Set.EqOn (⇑(g * g')) 1 {x | c ≤ g' x}
⊢ (↑(algebraMapCLM ℝ≥0 𝕜)).comp (g * g') = (↑(algebraMapCLM ℝ≥0 𝕜)).comp g * (↑(algebraMapCLM ℝ≥0 𝕜)).comp g'
state_after: case h.e'_4.h
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
g : C(X, ℝ≥0)
hg : ∀ (x : X), (g * g') x ≤ 1
hgc : Set.EqOn (⇑(g * g')) 1 {x | c ≤ g' x}
a✝ : X
⊢ ((↑(algebraMapCLM ℝ≥0 𝕜)).comp (g * g')) a✝ = ((↑(algebraMapCLM ℝ≥0 𝕜)).comp g * (↑(algebraMapCLM ℝ≥0 𝕜)).comp g') a✝
tactic: ext
state_before: case h.e'_4.h
X : Type u_1
𝕜 : Type u_2
inst✝³ : RCLike 𝕜
inst✝² : TopologicalSpace X
inst✝¹ : CompactSpace X
inst✝ : T2Space X
I : Ideal C(X, 𝕜)
f : C(X, 𝕜)
hf : f ∈ idealOfSet 𝕜 (setOfIdeal I)
ε : ℝ≥0
hε : 0 < ε
t : Set X := {x | ε / 2 ≤ ‖f x‖₊}
ht : IsClosed t
htI : Disjoint t (setOfIdeal I)ᶜ
g' : C(X, ℝ≥0)
hI' : (↑(algebraMapCLM ℝ≥0 𝕜)).comp g' ∈ I
hgt' : ∀ x ∈ t, 0 < g' x
c : ℝ≥0
hc : c > 0
hgc' : ∀ y ∈ t, c ≤ g' y
g : C(X, ℝ≥0)
hg : ∀ (x : X), (g * g') x ≤ 1
hgc : Set.EqOn (⇑(g * g')) 1 {x | c ≤ g' x}
a✝ : X
⊢ ((↑(algebraMapCLM ℝ≥0 𝕜)).comp (g * g')) a✝ = ((↑(algebraMapCLM ℝ≥0 𝕜)).comp g * (↑(algebraMapCLM ℝ≥0 𝕜)).comp g') a✝
state_after: no goals
tactic: simp only [algebraMapCLM_coe, comp_apply, mul_apply, ContinuousMap.coe_coe, map_mul]