Theorem: Subalgebra.topologicalClosure_comap_homeomorph
File: Mathlib/Topology/Algebra/Algebra.lean

Proof steps:
state_before: R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ comap f s.topologicalClosure = (comap f s).topologicalClosure
state_after: case h
R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ ↑(comap f s.topologicalClosure) = ↑(comap f s).topologicalClosure
tactic: apply SetLike.ext'
state_before: case h
R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ ↑(comap f s.topologicalClosure) = ↑(comap f s).topologicalClosure
state_after: case h
R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ ↑(comap f s.topologicalClosure) = closure ↑(comap f s)
tactic: simp only [Subalgebra.topologicalClosure_coe]
state_before: case h
R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ ↑(comap f s.topologicalClosure) = closure ↑(comap f s)
state_after: case h
R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ ⇑f ⁻¹' ↑s.topologicalClosure = closure (⇑f ⁻¹' ↑s)
tactic: simp only [Subalgebra.coe_comap, Subsemiring.coe_comap, AlgHom.coe_toRingHom]
state_before: case h
R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ ⇑f ⁻¹' ↑s.topologicalClosure = closure (⇑f ⁻¹' ↑s)
state_after: case h
R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ ⇑f' ⁻¹' ↑s.topologicalClosure = closure (⇑f' ⁻¹' ↑s)
tactic: rw [w]
state_before: case h
R : Type u_1
inst✝⁸ : CommSemiring R
A : Type u
inst✝⁷ : TopologicalSpace A
inst✝⁶ : Semiring A
inst✝⁵ : Algebra R A
inst✝⁴ : TopologicalSemiring A
s : Subalgebra R A
B : Type u_2
inst✝³ : TopologicalSpace B
inst✝² : Ring B
inst✝¹ : TopologicalRing B
inst✝ : Algebra R B
f : B →ₐ[R] A
f' : B ≃ₜ A
w : ⇑f = ⇑f'
⊢ ⇑f' ⁻¹' ↑s.topologicalClosure = closure (⇑f' ⁻¹' ↑s)
state_after: no goals
tactic: exact f'.preimage_closure _