# mathlibdocumentation

topology.homeomorph

@[nolint]
structure homeomorph (α : Type u_5) (β : Type u_6)  :
Type (max u_5 u_6)
• to_equiv : α β
• continuous_to_fun : . "continuity'"
• continuous_inv_fun : . "continuity'"

Homeomorphism between α and β, also called topological isomorphism

@[instance]
def homeomorph.has_coe_to_fun {α : Type u_1} {β : Type u_2}  :

Equations
@[simp]
theorem homeomorph.homeomorph_mk_coe {α : Type u_1} {β : Type u_2} (a : α β) (b : . "continuity'") (c : . "continuity'") :

theorem homeomorph.coe_eq_to_equiv {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) (a : α) :
h a = (h.to_equiv) a

def homeomorph.refl (α : Type u_1)  :
α ≃ₜ α

Identity map as a homeomorphism.

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def homeomorph.trans {α : Type u_1} {β : Type u_2} {γ : Type u_3}  :
α ≃ₜ ββ ≃ₜ γα ≃ₜ γ

Composition of two homeomorphisms.

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def homeomorph.symm {α : Type u_1} {β : Type u_2}  :
α ≃ₜ ββ ≃ₜ α

Inverse of a homeomorphism.

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@[simp]
theorem homeomorph.homeomorph_mk_coe_symm {α : Type u_1} {β : Type u_2} (a : α β) (b : . "continuity'") (c : . "continuity'") :

theorem homeomorph.continuous {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

def homeomorph.change_inv {α : Type u_1} {β : Type u_2} (f : α ≃ₜ β) (g : β → α) :
α ≃ₜ β

Change the homeomorphism f to make the inverse function definitionally equal to g.

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theorem homeomorph.symm_comp_self {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

theorem homeomorph.self_comp_symm {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

theorem homeomorph.range_coe {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

theorem homeomorph.image_symm {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

theorem homeomorph.preimage_symm {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :
=

theorem homeomorph.induced_eq {α : Type u_1} {β : Type u_2} [tα : topological_space α] [tβ : topological_space β] (h : α ≃ₜ β) :
=

theorem homeomorph.coinduced_eq {α : Type u_1} {β : Type u_2} [tα : topological_space α] [tβ : topological_space β] (h : α ≃ₜ β) :

theorem homeomorph.embedding {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

theorem homeomorph.compact_image {α : Type u_1} {β : Type u_2} {s : set α} (h : α ≃ₜ β) :

theorem homeomorph.compact_preimage {α : Type u_1} {β : Type u_2} {s : set β} (h : α ≃ₜ β) :

theorem homeomorph.dense_embedding {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

theorem homeomorph.is_open_map {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

theorem homeomorph.is_closed_map {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

theorem homeomorph.closed_embedding {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

@[simp]
theorem homeomorph.is_open_preimage {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) {s : set β} :

def homeomorph.homeomorph_of_continuous_open {α : Type u_1} {β : Type u_2} (e : α β) :
α ≃ₜ β

If an bijective map e : α ≃ β is continuous and open, then it is a homeomorphism.

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theorem homeomorph.comp_continuous_on_iff {α : Type u_1} {β : Type u_2} {γ : Type u_3} (h : α ≃ₜ β) (f : γ → α) (s : set γ) :

theorem homeomorph.comp_continuous_iff {α : Type u_1} {β : Type u_2} {γ : Type u_3} (h : α ≃ₜ β) (f : γ → α) :

theorem homeomorph.quotient_map {α : Type u_1} {β : Type u_2} (h : α ≃ₜ β) :

def homeomorph.set_congr {α : Type u_1} {s t : set α} :
s = ts ≃ₜ t

If two sets are equal, then they are homeomorphic.

Equations
def homeomorph.sum_congr {α : Type u_1} {β : Type u_2} {γ : Type u_3} {δ : Type u_4}  :
α ≃ₜ βγ ≃ₜ δα γ ≃ₜ β δ

Sum of two homeomorphisms.

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def homeomorph.prod_congr {α : Type u_1} {β : Type u_2} {γ : Type u_3} {δ : Type u_4}  :
α ≃ₜ βγ ≃ₜ δα × γ ≃ₜ β × δ

Product of two homeomorphisms.

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def homeomorph.prod_comm (α : Type u_1) (β : Type u_2)  :
α × β ≃ₜ β × α

α × β is homeomorphic to β × α.

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def homeomorph.prod_assoc (α : Type u_1) (β : Type u_2) (γ : Type u_3)  :
× β) × γ ≃ₜ α × β × γ

(α × β) × γ is homeomorphic to α × (β × γ).

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def homeomorph.ulift {α : Type u}  :
≃ₜ α

ulift α is homeomorphic to α.

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def homeomorph.sum_prod_distrib {α : Type u_1} {β : Type u_2} {γ : Type u_3}  :
β) × γ ≃ₜ α × γ β × γ

(α ⊕ β) × γ is homeomorphic to α × γ ⊕ β × γ.

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def homeomorph.prod_sum_distrib {α : Type u_1} {β : Type u_2} {γ : Type u_3}  :
α × γ) ≃ₜ α × β α × γ

α × (β ⊕ γ) is homeomorphic to α × β ⊕ α × γ.

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def homeomorph.sigma_prod_distrib {β : Type u_2} {ι : Type u_5} {σ : ι → Type u_6} [Π (i : ι), topological_space (σ i)] :
(Σ (i : ι), σ i) × β ≃ₜ Σ (i : ι), σ i × β

(Σ i, σ i) × β is homeomorphic to Σ i, (σ i × β).

Equations