Theorem: isProperMap_of_comp_of_surj
File: Mathlib/Topology/Maps/Proper/Basic.lean

Proof steps:
state_before: X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
⊢ IsProperMap g
state_after: X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
ℱ : Filter Y
z : Z
h : MapClusterPt z ℱ g
⊢ ∃ x, g x = z ∧ ClusterPt x ℱ
tactic: refine ⟨hg, fun ℱ z h ↦ ?_⟩
state_before: X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
ℱ : Filter Y
z : Z
h : MapClusterPt z ℱ g
⊢ ∃ x, g x = z ∧ ClusterPt x ℱ
state_after: X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
ℱ : Filter Y
z : Z
h : MapClusterPt z (comap f ℱ) (g ∘ f)
⊢ ∃ x, g x = z ∧ ClusterPt x ℱ
tactic: rw [← ℱ.map_comap_of_surjective f_surj, ← mapClusterPt_comp] at h
state_before: X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
ℱ : Filter Y
z : Z
h : MapClusterPt z (comap f ℱ) (g ∘ f)
⊢ ∃ x, g x = z ∧ ClusterPt x ℱ
state_after: case intro.intro
X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
ℱ : Filter Y
x : X
hx : ClusterPt x (comap f ℱ)
h : MapClusterPt ((g ∘ f) x) (comap f ℱ) (g ∘ f)
⊢ ∃ x_1, g x_1 = (g ∘ f) x ∧ ClusterPt x_1 ℱ
tactic: rcases hgf.clusterPt_of_mapClusterPt h with ⟨x, rfl, hx⟩
state_before: case intro.intro
X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
ℱ : Filter Y
x : X
hx : ClusterPt x (comap f ℱ)
h : MapClusterPt ((g ∘ f) x) (comap f ℱ) (g ∘ f)
⊢ ∃ x_1, g x_1 = (g ∘ f) x ∧ ClusterPt x_1 ℱ
state_after: case intro.intro
X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
ℱ : Filter Y
x : X
hx : ClusterPt x (comap f ℱ)
h : MapClusterPt ((g ∘ f) x) (comap f ℱ) (g ∘ f)
⊢ ∃ x_1, g x_1 = (g ∘ f) x ∧ ClusterPt x_1 (map f (comap f ℱ))
tactic: rw [← ℱ.map_comap_of_surjective f_surj]
state_before: case intro.intro
X : Type u_1
Y : Type u_2
Z : Type u_3
W : Type u_4
ι : Type u_5
inst✝³ : TopologicalSpace X
inst✝² : TopologicalSpace Y
inst✝¹ : TopologicalSpace Z
inst✝ : TopologicalSpace W
f : X → Y
g : Y → Z
hf : Continuous f
hg : Continuous g
hgf : IsProperMap (g ∘ f)
f_surj : Surjective f
ℱ : Filter Y
x : X
hx : ClusterPt x (comap f ℱ)
h : MapClusterPt ((g ∘ f) x) (comap f ℱ) (g ∘ f)
⊢ ∃ x_1, g x_1 = (g ∘ f) x ∧ ClusterPt x_1 (map f (comap f ℱ))
state_after: no goals
tactic: exact ⟨f x, rfl, hx.map hf.continuousAt tendsto_map⟩