Theorem: TopologicalSpace.NoetherianSpace.finite_irreducibleComponents
File: Mathlib/Topology/NoetherianSpace.lean

Proof steps:
state_before: α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
⊢ (irreducibleComponents α).Finite
state_after: case intro.intro.intro.intro
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
S : Set (Set α)
hSf : S.Finite
hSc : ∀ t ∈ S, IsClosed t
hSi : ∀ t ∈ S, IsIrreducible t
hSU : Set.univ = ⋃₀ S
⊢ (irreducibleComponents α).Finite
tactic: obtain ⟨S : Set (Set α), hSf, hSc, hSi, hSU⟩ :=
    NoetherianSpace.exists_finite_set_isClosed_irreducible isClosed_univ (α := α)
state_before: case intro.intro.intro.intro
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
S : Set (Set α)
hSf : S.Finite
hSc : ∀ t ∈ S, IsClosed t
hSi : ∀ t ∈ S, IsIrreducible t
hSU : Set.univ = ⋃₀ S
⊢ (irreducibleComponents α).Finite
state_after: case intro.intro.intro.intro
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
S : Set (Set α)
hSf : S.Finite
hSc : ∀ t ∈ S, IsClosed t
hSi : ∀ t ∈ S, IsIrreducible t
hSU : Set.univ = ⋃₀ S
s : Set α
hs : s ∈ irreducibleComponents α
⊢ s ∈ S
tactic: refine hSf.subset fun s hs => ?_
state_before: case intro.intro.intro.intro
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
S : Set (Set α)
hSf : S.Finite
hSc : ∀ t ∈ S, IsClosed t
hSi : ∀ t ∈ S, IsIrreducible t
hSU : Set.univ = ⋃₀ S
s : Set α
hs : s ∈ irreducibleComponents α
⊢ s ∈ S
state_after: case intro.intro.intro.intro.intro
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
s : Set α
hs : s ∈ irreducibleComponents α
S : Finset (Set α)
hSc : ∀ t ∈ ↑S, IsClosed t
hSi : ∀ t ∈ ↑S, IsIrreducible t
hSU : Set.univ = ⋃₀ ↑S
⊢ s ∈ ↑S
tactic: lift S to Finset (Set α) using hSf
state_before: case intro.intro.intro.intro.intro
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
s : Set α
hs : s ∈ irreducibleComponents α
S : Finset (Set α)
hSc : ∀ t ∈ ↑S, IsClosed t
hSi : ∀ t ∈ ↑S, IsIrreducible t
hSU : Set.univ = ⋃₀ ↑S
⊢ s ∈ ↑S
state_after: case intro.intro.intro.intro.intro.intro.intro
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
s : Set α
hs : s ∈ irreducibleComponents α
S : Finset (Set α)
hSc : ∀ t ∈ ↑S, IsClosed t
hSi : ∀ t ∈ ↑S, IsIrreducible t
hSU : Set.univ = ⋃₀ ↑S
t : Set α
htS : t ∈ S
ht : s ⊆ t
⊢ s ∈ ↑S
tactic: rcases isIrreducible_iff_sUnion_closed.1 hs.1 S hSc (hSU ▸ Set.subset_univ _) with ⟨t, htS, ht⟩
state_before: case intro.intro.intro.intro.intro.intro.intro
α : Type u_1
β : Type u_2
inst✝² : TopologicalSpace α
inst✝¹ : TopologicalSpace β
inst✝ : NoetherianSpace α
s : Set α
hs : s ∈ irreducibleComponents α
S : Finset (Set α)
hSc : ∀ t ∈ ↑S, IsClosed t
hSi : ∀ t ∈ ↑S, IsIrreducible t
hSU : Set.univ = ⋃₀ ↑S
t : Set α
htS : t ∈ S
ht : s ⊆ t
⊢ s ∈ ↑S
state_after: no goals
tactic: rwa [ht.antisymm (hs.2 (hSi _ htS) ht)]