Documentation

Mathlib.Topology.Order

Ordering on topologies and (co)induced topologies #

Topologies on a fixed type α are ordered, by reverse inclusion. That is, for topologies t₁ and t₂ on α, we write t₁ ≤ t₂≤ t₂ if every set open in t₂ is also open in t₁. (One also calls t₁ finer than t₂, and t₂ coarser than t₁.)

Any function f : α → β→ β induces

TopologicalSpace.induced f : TopologicalSpace β → TopologicalSpace α→ TopologicalSpace α;
TopologicalSpace.coinduced f : TopologicalSpace α → TopologicalSpace β→ TopologicalSpace β.

Continuity, the ordering on topologies and (co)induced topologies are related as follows:

The identity map (α, t₁) → (α, t₂)→ (α, t₂) is continuous iff t₁ ≤ t₂≤ t₂.
A map f : (α, t) → (β, u)→ (β, u) is continuous
- iff t ≤ TopologicalSpace.induced f u≤ TopologicalSpace.induced f u (continuous_iff_le_induced)
- iff TopologicalSpace.coinduced f t ≤ u≤ u (continuous_iff_coinduced_le).

Topologies on α form a complete lattice, with ⊥⊥ the discrete topology and ⊤⊤ the indiscrete topology.

For a function f : α → β→ β, (TopologicalSpace.coinduced f, TopologicalSpace.induced f) is a Galois connection between topologies on α and topologies on β.

Implementation notes #

There is a Galois insertion between topologies on α (with the inclusion ordering) and all collections of sets in α. The complete lattice structure on topologies on α is defined as the reverse of the one obtained via this Galois insertion. More precisely, we use the corresponding Galois coinsertion between topologies on α (with the reversed inclusion ordering) and collections of sets in α (with the reversed inclusion ordering).

Tags #

finer, coarser, induced topology, coinduced topology

inductive TopologicalSpace.GenerateOpen {α : Type u} (g : Set (Set α)) :

Set α → Prop

basic: ∀ {α : Type u} {g : Set (Set α)} (s : Set α), s ∈ g → TopologicalSpace.GenerateOpen g s
univ: ∀ {α : Type u} {g : Set (Set α)}, TopologicalSpace.GenerateOpen g Set.univ
inter: ∀ {α : Type u} {g : Set (Set α)} (s t : Set α), TopologicalSpace.GenerateOpen g s → TopologicalSpace.GenerateOpen g t → TopologicalSpace.GenerateOpen g (s ∩ t)
unionₛ: ∀ {α : Type u} {g : Set (Set α)} (S : Set (Set α)), (∀ (s : Set α), s ∈ S → TopologicalSpace.GenerateOpen g s) → TopologicalSpace.GenerateOpen g (⋃₀ S)

The open sets of the least topology containing a collection of basic sets.

Instances For

def TopologicalSpace.generateFrom {α : Type u} (g : Set (Set α)) :

TopologicalSpace α

The smallest topological space containing the collection g of basic sets

Equations

One or more equations did not get rendered due to their size.

theorem TopologicalSpace.isOpen_generateFrom_of_mem {α : Type u} {g : Set (Set α)} {s : Set α} (hs : s ∈ g) :

theorem TopologicalSpace.nhds_generateFrom {α : Type u} {g : Set (Set α)} {a : α} :

nhds a = ⨅ s, ⨅ h, Filter.principal s

theorem TopologicalSpace.tendsto_nhds_generateFrom {α : Type u} {β : Type u_1} {m : α → β} {f : Filter α} {g : Set (Set β)} {b : β} (h : ∀ (s : Set β), s ∈ g → b ∈ s → m ⁻¹' s ∈ f) :

Filter.Tendsto m f (nhds b)

def TopologicalSpace.mkOfNhds {α : Type u} (n : α → Filter α) :

TopologicalSpace α

Construct a topology on α given the filter of neighborhoods of each point of α.

Equations

One or more equations did not get rendered due to their size.

theorem TopologicalSpace.nhds_mkOfNhds {α : Type u} (n : α → Filter α) (a : α) (h₀ : pure ≤ n) (h₁ : ∀ (a : α) (s : Set α), s ∈ n a → ∃ t, t ∈ n a ∧ t ⊆ s ∧ ∀ (a' : α), a' ∈ t → s ∈ n a') :

nhds a = n a

theorem TopologicalSpace.nhds_mkOfNhds_single {α : Type u} [inst : DecidableEq α] {a₀ : α} {l : Filter α} (h : pure a₀ ≤ l) (b : α) :

nhds b = Function.update pure a₀ l b

theorem TopologicalSpace.nhds_mkOfNhds_filterBasis {α : Type u} (B : α → FilterBasis α) (a : α) (h₀ : ∀ (x : α) (n : Set α), n ∈ B x → x ∈ n) (h₁ : ∀ (x : α) (n : Set α), n ∈ B x → ∃ n₁, n₁ ∈ B x ∧ n₁ ⊆ n ∧ ∀ (x' : α), x' ∈ n₁ → ∃ n₂, n₂ ∈ B x' ∧ n₂ ⊆ n) :

nhds a = FilterBasis.filter (B a)

instance TopologicalSpace.instPartialOrderTopologicalSpace {α : Type u} :

PartialOrder (TopologicalSpace α)

The ordering on topologies on the type α. t ≤ s≤ s if every set open in s is also open in t (t is finer than s).

Equations

One or more equations did not get rendered due to their size.

theorem TopologicalSpace.le_def {α : Type u_1} {t : TopologicalSpace α} {s : TopologicalSpace α} :

t ≤ s ↔ IsOpen ≤ IsOpen

theorem TopologicalSpace.le_generateFrom_iff_subset_isOpen {α : Type u} {g : Set (Set α)} {t : TopologicalSpace α} :

t ≤ TopologicalSpace.generateFrom g ↔ g ⊆ { s | IsOpen s }

def TopologicalSpace.mkOfClosure {α : Type u} (s : Set (Set α)) (hs : { u | TopologicalSpace.GenerateOpen s u } = s) :

TopologicalSpace α

If s equals the collection of open sets in the topology it generates, then s defines a topology.

Equations

One or more equations did not get rendered due to their size.

theorem TopologicalSpace.mkOfClosure_sets {α : Type u} {s : Set (Set α)} {hs : { u | TopologicalSpace.GenerateOpen s u } = s} :

TopologicalSpace.mkOfClosure s hs = TopologicalSpace.generateFrom s

theorem TopologicalSpace.gc_generateFrom (α : Type u_1) :

GaloisConnection (fun t => ↑OrderDual.toDual { s | IsOpen s }) (TopologicalSpace.generateFrom ∘ ↑OrderDual.ofDual)

def TopologicalSpace.gciGenerateFrom (α : Type u_1) :

GaloisCoinsertion (fun t => ↑OrderDual.toDual { s | IsOpen s }) (TopologicalSpace.generateFrom ∘ ↑OrderDual.ofDual)

The Galois coinsertion between TopologicalSpace α and (Set (Set α))ᵒᵈ whose lower part sends a topology to its collection of open subsets, and whose upper part sends a collection of subsets of α to the topology they generate.

Equations

One or more equations did not get rendered due to their size.

instance TopologicalSpace.instCompleteLatticeTopologicalSpace {α : Type u} :

CompleteLattice (TopologicalSpace α)

Topologies on α form a complete lattice, with ⊥⊥ the discrete topology and ⊤⊤ the indiscrete topology. The infimum of a collection of topologies is the topology generated by all their open sets, while the supremum is the topology whose open sets are those sets open in every member of the collection.

Equations

TopologicalSpace.instCompleteLatticeTopologicalSpace = GaloisCoinsertion.liftCompleteLattice (TopologicalSpace.gciGenerateFrom α)

theorem TopologicalSpace.generateFrom_anti {α : Type u_1} {g₁ : Set (Set α)} {g₂ : Set (Set α)} (h : g₁ ⊆ g₂) :

TopologicalSpace.generateFrom g₂ ≤ TopologicalSpace.generateFrom g₁

theorem TopologicalSpace.generateFrom_setOf_isOpen {α : Type u} (t : TopologicalSpace α) :

TopologicalSpace.generateFrom { s | IsOpen s } = t

theorem TopologicalSpace.leftInverse_generateFrom {α : Type u} :

Function.LeftInverse TopologicalSpace.generateFrom fun t => { s | IsOpen s }

theorem TopologicalSpace.generateFrom_surjective {α : Type u} :

Function.Surjective TopologicalSpace.generateFrom

theorem TopologicalSpace.setOf_isOpen_injective {α : Type u} :

Function.Injective fun t => { s | IsOpen s }

theorem IsOpen.mono {α : Type u_1} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {s : Set α} (hs : IsOpen s) (h : t₁ ≤ t₂) :

theorem IsClosed.mono {α : Type u_1} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {s : Set α} (hs : IsClosed s) (h : t₁ ≤ t₂) :

theorem isOpen_implies_isOpen_iff {α : Type u_1} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} :

(∀ (s : Set α), IsOpen s → IsOpen s) ↔ t₂ ≤ t₁

theorem TopologicalSpace.isOpen_top_iff {α : Type u_1} (U : Set α) :

IsOpen U ↔ U = ∅ ∨ U = Set.univ

The only open sets in the indiscrete topology are the empty set and the whole space.

class DiscreteTopology (α : Type u_1) [t : TopologicalSpace α] :

The TopologicalSpace structure on a type with discrete topology is equal to ⊥⊥.
eq_bot : t = ⊥

A topological space is discrete if every set is open, that is, its topology equals the discrete topology ⊥⊥.

Instances

theorem discreteTopology_bot (α : Type u_1) :

DiscreteTopology α

@[simp]

theorem isOpen_discrete {α : Type u_1} [inst : TopologicalSpace α] [inst : DiscreteTopology α] (s : Set α) :

@[simp]

theorem isClosed_discrete {α : Type u_1} [inst : TopologicalSpace α] [inst : DiscreteTopology α] (s : Set α) :

theorem continuous_of_discreteTopology {α : Type u_2} {β : Type u_1} [inst : TopologicalSpace α] [inst : DiscreteTopology α] [inst : TopologicalSpace β] {f : α → β} :

@[simp]

theorem nhds_discrete (α : Type u_1) [inst : TopologicalSpace α] [inst : DiscreteTopology α] :

nhds = pure

theorem mem_nhds_discrete {α : Type u_1} [inst : TopologicalSpace α] [inst : DiscreteTopology α] {x : α} {s : Set α} :

s ∈ nhds x ↔ x ∈ s

theorem le_of_nhds_le_nhds {α : Type u_1} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} (h : ∀ (x : α), nhds x ≤ nhds x) :

t₁ ≤ t₂

theorem eq_of_nhds_eq_nhds {α : Type u_1} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} (h : ∀ (x : α), nhds x = nhds x) :

t₁ = t₂

theorem eq_bot_of_singletons_open {α : Type u_1} {t : TopologicalSpace α} (h : ∀ (x : α), IsOpen {x}) :

theorem forall_open_iff_discrete {X : Type u_1} [inst : TopologicalSpace X] :

(∀ (s : Set X), IsOpen s) ↔ DiscreteTopology X

theorem singletons_open_iff_discrete {X : Type u_1} [inst : TopologicalSpace X] :

(∀ (a : X), IsOpen {a}) ↔ DiscreteTopology X

theorem discreteTopology_iff_singleton_mem_nhds {α : Type u_1} [inst : TopologicalSpace α] :

DiscreteTopology α ↔ ∀ (x : α), {x} ∈ nhds x

theorem discreteTopology_iff_nhds {α : Type u_1} [inst : TopologicalSpace α] :

DiscreteTopology α ↔ ∀ (x : α), nhds x = pure x

This lemma characterizes discrete topological spaces as those whose singletons are neighbourhoods.

theorem discreteTopology_iff_nhds_ne {α : Type u_1} [inst : TopologicalSpace α] :

DiscreteTopology α ↔ ∀ (x : α), nhdsWithin x ({x}ᶜ) = ⊥

def TopologicalSpace.induced {α : Type u} {β : Type v} (f : α → β) (t : TopologicalSpace β) :

TopologicalSpace α

Given f : α → β→ β and a topology on β, the induced topology on α is the collection of sets that are preimages of some open set in β. This is the coarsest topology that makes f continuous.

Equations

One or more equations did not get rendered due to their size.

theorem isOpen_induced_iff {α : Type u_2} {β : Type u_1} [t : TopologicalSpace β] {s : Set α} {f : α → β} :

IsOpen s ↔ ∃ t, IsOpen t ∧ f ⁻¹' t = s

theorem isClosed_induced_iff {α : Type u_2} {β : Type u_1} [t : TopologicalSpace β] {s : Set α} {f : α → β} :

IsClosed s ↔ ∃ t, IsClosed t ∧ f ⁻¹' t = s

def TopologicalSpace.coinduced {α : Type u} {β : Type v} (f : α → β) (t : TopologicalSpace α) :

TopologicalSpace β

Given f : α → β→ β and a topology on α, the coinduced topology on β is defined such that s : Set β is open if the preimage of s is open. This is the finest topology that makes f continuous.

Equations

One or more equations did not get rendered due to their size.

theorem isOpen_coinduced {α : Type u_1} {β : Type u_2} {t : TopologicalSpace α} {s : Set β} {f : α → β} :

IsOpen s ↔ IsOpen (f ⁻¹' s)

theorem preimage_nhds_coinduced {α : Type u_1} {β : Type u_2} [inst : TopologicalSpace α] {π : α → β} {s : Set β} {a : α} (hs : s ∈ nhds (π a)) :

π ⁻¹' s ∈ nhds a

theorem Continuous.coinduced_le {α : Type u_1} {β : Type u_2} {t : TopologicalSpace α} {t' : TopologicalSpace β} {f : α → β} (h : Continuous f) :

TopologicalSpace.coinduced f t ≤ t'

theorem coinduced_le_iff_le_induced {α : Type u_1} {β : Type u_2} {f : α → β} {tα : TopologicalSpace α} {tβ : TopologicalSpace β} :

TopologicalSpace.coinduced f tα ≤ tβ ↔ tα ≤ TopologicalSpace.induced f tβ

theorem Continuous.le_induced {α : Type u_1} {β : Type u_2} {t : TopologicalSpace α} {t' : TopologicalSpace β} {f : α → β} (h : Continuous f) :

t ≤ TopologicalSpace.induced f t'

theorem gc_coinduced_induced {α : Type u_1} {β : Type u_2} (f : α → β) :

GaloisConnection (TopologicalSpace.coinduced f) (TopologicalSpace.induced f)

theorem induced_mono {α : Type u_1} {β : Type u_2} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {g : β → α} (h : t₁ ≤ t₂) :

TopologicalSpace.induced g t₁ ≤ TopologicalSpace.induced g t₂

theorem coinduced_mono {α : Type u_1} {β : Type u_2} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {f : α → β} (h : t₁ ≤ t₂) :

TopologicalSpace.coinduced f t₁ ≤ TopologicalSpace.coinduced f t₂

@[simp]

theorem induced_top {α : Type u_2} {β : Type u_1} {g : β → α} :

TopologicalSpace.induced g ⊤ = ⊤

@[simp]

theorem induced_inf {α : Type u_2} {β : Type u_1} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {g : β → α} :

TopologicalSpace.induced g (t₁ ⊓ t₂) = TopologicalSpace.induced g t₁ ⊓ TopologicalSpace.induced g t₂

@[simp]

theorem induced_infᵢ {α : Type u_1} {β : Type u_2} {g : β → α} {ι : Sort w} {t : ι → TopologicalSpace α} :

TopologicalSpace.induced g (⨅ i, t i) = ⨅ i, TopologicalSpace.induced g (t i)

@[simp]

theorem coinduced_bot {α : Type u_2} {β : Type u_1} {f : α → β} :

TopologicalSpace.coinduced f ⊥ = ⊥

@[simp]

theorem coinduced_sup {α : Type u_2} {β : Type u_1} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {f : α → β} :

TopologicalSpace.coinduced f (t₁ ⊔ t₂) = TopologicalSpace.coinduced f t₁ ⊔ TopologicalSpace.coinduced f t₂

@[simp]

theorem coinduced_supᵢ {α : Type u_1} {β : Type u_2} {f : α → β} {ι : Sort w} {t : ι → TopologicalSpace α} :

TopologicalSpace.coinduced f (⨆ i, t i) = ⨆ i, TopologicalSpace.coinduced f (t i)

theorem induced_id {α : Type u_1} [t : TopologicalSpace α] :

TopologicalSpace.induced id t = t

theorem induced_compose {α : Type u_2} {β : Type u_3} {γ : Type u_1} [tγ : TopologicalSpace γ] {f : α → β} {g : β → γ} :

TopologicalSpace.induced f (TopologicalSpace.induced g tγ) = TopologicalSpace.induced (g ∘ f) tγ

theorem induced_const {α : Type u_1} {β : Type u_2} [t : TopologicalSpace α] {x : α} :

TopologicalSpace.induced (fun x => x) t = ⊤

theorem coinduced_id {α : Type u_1} [t : TopologicalSpace α] :

TopologicalSpace.coinduced id t = t

theorem coinduced_compose {α : Type u_1} {β : Type u_3} {γ : Type u_2} [tα : TopologicalSpace α] {f : α → β} {g : β → γ} :

TopologicalSpace.coinduced g (TopologicalSpace.coinduced f tα) = TopologicalSpace.coinduced (g ∘ f) tα

theorem Equiv.induced_symm {α : Type u_1} {β : Type u_2} (e : α ≃ β) :

TopologicalSpace.induced ↑(Equiv.symm e) = TopologicalSpace.coinduced ↑e

theorem Equiv.coinduced_symm {α : Type u_1} {β : Type u_2} (e : α ≃ β) :

TopologicalSpace.coinduced ↑(Equiv.symm e) = TopologicalSpace.induced ↑e

instance inhabitedTopologicalSpace {α : Type u} :

Inhabited (TopologicalSpace α)

Equations

inhabitedTopologicalSpace = { default := ⊥ }

instance Subsingleton.uniqueTopologicalSpace {α : Type u} [inst : Subsingleton α] :

Unique (TopologicalSpace α)

Equations

Subsingleton.uniqueTopologicalSpace = { toInhabited := { default := ⊥ }, uniq := (_ : ∀ (t : TopologicalSpace α), t = ⊥) }

instance Subsingleton.discreteTopology {α : Type u} [t : TopologicalSpace α] [inst : Subsingleton α] :

DiscreteTopology α

Equations

@Subsingleton.discreteTopology = @Subsingleton.discreteTopology.proof_1

instance instTopologicalSpaceEmpty :

TopologicalSpace Empty

Equations

instTopologicalSpaceEmpty = ⊥

instance instDiscreteTopologyEmptyInstTopologicalSpaceEmpty :

DiscreteTopology Empty

Equations

instDiscreteTopologyEmptyInstTopologicalSpaceEmpty = instDiscreteTopologyEmptyInstTopologicalSpaceEmpty.proof_1

instance instTopologicalSpacePEmpty :

TopologicalSpace PEmpty

Equations

instTopologicalSpacePEmpty = ⊥

instance instDiscreteTopologyPEmptyInstTopologicalSpacePEmpty :

DiscreteTopology PEmpty

Equations

instDiscreteTopologyPEmptyInstTopologicalSpacePEmpty = instDiscreteTopologyPEmptyInstTopologicalSpacePEmpty.proof_1

instance instTopologicalSpacePUnit :

TopologicalSpace PUnit

Equations

instTopologicalSpacePUnit = ⊥

instance instDiscreteTopologyPUnitInstTopologicalSpacePUnit :

DiscreteTopology PUnit

Equations

instDiscreteTopologyPUnitInstTopologicalSpacePUnit = instDiscreteTopologyPUnitInstTopologicalSpacePUnit.proof_1

instance instTopologicalSpaceBool :

TopologicalSpace Bool

Equations

instTopologicalSpaceBool = ⊥

instance instDiscreteTopologyBoolInstTopologicalSpaceBool :

DiscreteTopology Bool

Equations

instDiscreteTopologyBoolInstTopologicalSpaceBool = instDiscreteTopologyBoolInstTopologicalSpaceBool.proof_1

instance instTopologicalSpaceNat :

TopologicalSpace ℕ

Equations

instTopologicalSpaceNat = ⊥

instance instDiscreteTopologyNatInstTopologicalSpaceNat :

DiscreteTopology ℕ

Equations

instDiscreteTopologyNatInstTopologicalSpaceNat = instDiscreteTopologyNatInstTopologicalSpaceNat.proof_1

instance instTopologicalSpaceInt :

TopologicalSpace ℤ

Equations

instTopologicalSpaceInt = ⊥

instance instDiscreteTopologyIntInstTopologicalSpaceInt :

DiscreteTopology ℤ

Equations

instDiscreteTopologyIntInstTopologicalSpaceInt = instDiscreteTopologyIntInstTopologicalSpaceInt.proof_1

instance instTopologicalSpaceFin {n : ℕ} :

TopologicalSpace (Fin n)

Equations

instTopologicalSpaceFin = ⊥

instance instDiscreteTopologyFinInstTopologicalSpaceFin {n : ℕ} :

DiscreteTopology (Fin n)

Equations

@instDiscreteTopologyFinInstTopologicalSpaceFin = @instDiscreteTopologyFinInstTopologicalSpaceFin.proof_1

instance sierpinskiSpace :

TopologicalSpace Prop

Equations

sierpinskiSpace = TopologicalSpace.generateFrom {{True}}

theorem continuous_empty_function {α : Type u} {β : Type v} [inst : TopologicalSpace α] [inst : TopologicalSpace β] [inst : IsEmpty β] (f : α → β) :

theorem le_generateFrom {α : Type u} {t : TopologicalSpace α} {g : Set (Set α)} (h : ∀ (s : Set α), s ∈ g → IsOpen s) :

t ≤ TopologicalSpace.generateFrom g

theorem induced_generateFrom_eq {α : Type u_1} {β : Type u_2} {b : Set (Set β)} {f : α → β} :

TopologicalSpace.induced f (TopologicalSpace.generateFrom b) = TopologicalSpace.generateFrom (Set.preimage f '' b)

theorem le_induced_generateFrom {α : Type u_1} {β : Type u_2} [t : TopologicalSpace α] {b : Set (Set β)} {f : α → β} (h : ∀ (a : Set β), a ∈ b → IsOpen (f ⁻¹' a)) :

t ≤ TopologicalSpace.induced f (TopologicalSpace.generateFrom b)

def nhdsAdjoint {α : Type u} (a : α) (f : Filter α) :

TopologicalSpace α

This construction is left adjoint to the operation sending a topology on α to its neighborhood filter at a fixed point a : α.

Equations

One or more equations did not get rendered due to their size.

theorem gc_nhds {α : Type u} (a : α) :

GaloisConnection (nhdsAdjoint a) fun t => nhds a

theorem nhds_mono {α : Type u} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {a : α} (h : t₁ ≤ t₂) :

nhds a ≤ nhds a

theorem le_iff_nhds {α : Type u_1} (t : TopologicalSpace α) (t' : TopologicalSpace α) :

t ≤ t' ↔ ∀ (x : α), nhds x ≤ nhds x

theorem nhdsAdjoint_nhds {α : Type u_1} (a : α) (f : Filter α) :

nhds a = pure a ⊔ f

theorem nhdsAdjoint_nhds_of_ne {α : Type u_1} (a : α) (f : Filter α) {b : α} (h : b ≠ a) :

nhds b = pure b

theorem isOpen_singleton_nhdsAdjoint {α : Type u_1} {a : α} {b : α} (f : Filter α) (hb : b ≠ a) :

theorem le_nhdsAdjoint_iff' {α : Type u_1} (a : α) (f : Filter α) (t : TopologicalSpace α) :

t ≤ nhdsAdjoint a f ↔ nhds a ≤ pure a ⊔ f ∧ ∀ (b : α), b ≠ a → nhds b = pure b

theorem le_nhdsAdjoint_iff {α : Type u_1} (a : α) (f : Filter α) (t : TopologicalSpace α) :

t ≤ nhdsAdjoint a f ↔ nhds a ≤ pure a ⊔ f ∧ ∀ (b : α), b ≠ a → IsOpen {b}

theorem nhds_infᵢ {α : Type u} {ι : Sort u_1} {t : ι → TopologicalSpace α} {a : α} :

nhds a = ⨅ i, nhds a

theorem nhds_infₛ {α : Type u} {s : Set (TopologicalSpace α)} {a : α} :

nhds a = ⨅ t, ⨅ h, nhds a

theorem nhds_inf {α : Type u} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {a : α} :

nhds a = nhds a ⊓ nhds a

theorem nhds_top {α : Type u} {a : α} :

theorem isOpen_sup {α : Type u} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {s : Set α} :

IsOpen s ↔ IsOpen s ∧ IsOpen s

theorem continuous_iff_coinduced_le {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace β} :

Continuous f ↔ TopologicalSpace.coinduced f t₁ ≤ t₂

theorem continuous_iff_le_induced {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace β} :

Continuous f ↔ t₁ ≤ TopologicalSpace.induced f t₂

theorem continuous_generateFrom {α : Type u} {β : Type v} {f : α → β} {t : TopologicalSpace α} {b : Set (Set β)} (h : ∀ (s : Set β), s ∈ b → IsOpen (f ⁻¹' s)) :

theorem continuous_induced_dom {α : Type u} {β : Type v} {f : α → β} {t : TopologicalSpace β} :

theorem continuous_induced_rng {α : Type u} {β : Type v} {γ : Type u_1} {f : α → β} {g : γ → α} {t₂ : TopologicalSpace β} {t₁ : TopologicalSpace γ} :

Continuous g ↔ Continuous (f ∘ g)

theorem continuous_coinduced_rng {α : Type u} {β : Type v} {f : α → β} {t : TopologicalSpace α} :

theorem continuous_coinduced_dom {α : Type u} {β : Type v} {γ : Type u_1} {f : α → β} {g : β → γ} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace γ} :

Continuous g ↔ Continuous (g ∘ f)

theorem continuous_le_dom {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {t₃ : TopologicalSpace β} (h₁ : t₂ ≤ t₁) (h₂ : Continuous f) :

theorem continuous_le_rng {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace β} {t₃ : TopologicalSpace β} (h₁ : t₂ ≤ t₃) (h₂ : Continuous f) :

theorem continuous_sup_dom {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {t₃ : TopologicalSpace β} :

Continuous f ↔ Continuous f ∧ Continuous f

theorem continuous_sup_rng_left {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₃ : TopologicalSpace β} {t₂ : TopologicalSpace β} :

Continuous f → Continuous f

theorem continuous_sup_rng_right {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₃ : TopologicalSpace β} {t₂ : TopologicalSpace β} :

Continuous f → Continuous f

theorem continuous_supₛ_dom {α : Type u} {β : Type v} {f : α → β} {T : Set (TopologicalSpace α)} {t₂ : TopologicalSpace β} :

Continuous f ↔ ∀ (t : TopologicalSpace α), t ∈ T → Continuous f

theorem continuous_supₛ_rng {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : Set (TopologicalSpace β)} {t : TopologicalSpace β} (h₁ : t ∈ t₂) (hf : Continuous f) :

theorem continuous_supᵢ_dom {α : Type u} {β : Type v} {f : α → β} {ι : Sort u_1} {t₁ : ι → TopologicalSpace α} {t₂ : TopologicalSpace β} :

Continuous f ↔ ∀ (i : ι), Continuous f

theorem continuous_supᵢ_rng {α : Type u} {β : Type v} {f : α → β} {ι : Sort u_1} {t₁ : TopologicalSpace α} {t₂ : ι → TopologicalSpace β} {i : ι} (h : Continuous f) :

theorem continuous_inf_rng {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace β} {t₃ : TopologicalSpace β} :

Continuous f ↔ Continuous f ∧ Continuous f

theorem continuous_inf_dom_left {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {t₃ : TopologicalSpace β} :

Continuous f → Continuous f

theorem continuous_inf_dom_right {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {t₂ : TopologicalSpace α} {t₃ : TopologicalSpace β} :

Continuous f → Continuous f

theorem continuous_infₛ_dom {α : Type u} {β : Type v} {f : α → β} {t₁ : Set (TopologicalSpace α)} {t₂ : TopologicalSpace β} {t : TopologicalSpace α} (h₁ : t ∈ t₁) :

Continuous f → Continuous f

theorem continuous_infₛ_rng {α : Type u} {β : Type v} {f : α → β} {t₁ : TopologicalSpace α} {T : Set (TopologicalSpace β)} :

Continuous f ↔ ∀ (t : TopologicalSpace β), t ∈ T → Continuous f

theorem continuous_infᵢ_dom {α : Type u} {β : Type v} {f : α → β} {ι : Sort u_1} {t₁ : ι → TopologicalSpace α} {t₂ : TopologicalSpace β} {i : ι} :

Continuous f → Continuous f

theorem continuous_infᵢ_rng {α : Type u} {β : Type v} {f : α → β} {ι : Sort u_1} {t₁ : TopologicalSpace α} {t₂ : ι → TopologicalSpace β} :

Continuous f ↔ ∀ (i : ι), Continuous f

theorem continuous_bot {α : Type u} {β : Type v} {f : α → β} {t : TopologicalSpace β} :

theorem continuous_top {α : Type u} {β : Type v} {f : α → β} {t : TopologicalSpace α} :

theorem continuous_id_iff_le {α : Type u} {t : TopologicalSpace α} {t' : TopologicalSpace α} :

Continuous id ↔ t ≤ t'

theorem continuous_id_of_le {α : Type u} {t : TopologicalSpace α} {t' : TopologicalSpace α} (h : t ≤ t') :

theorem mem_nhds_induced {α : Type u} {β : Type v} [T : TopologicalSpace α] (f : β → α) (a : β) (s : Set β) :

s ∈ nhds a ↔ ∃ u, u ∈ nhds (f a) ∧ f ⁻¹' u ⊆ s

theorem nhds_induced {α : Type u} {β : Type v} [T : TopologicalSpace α] (f : β → α) (a : β) :

nhds a = Filter.comap f (nhds (f a))

theorem induced_iff_nhds_eq {α : Type u} {β : Type v} [tα : TopologicalSpace α] [tβ : TopologicalSpace β] (f : β → α) :

tβ = TopologicalSpace.induced f tα ↔ ∀ (b : β), nhds b = Filter.comap f (nhds (f b))

theorem map_nhds_induced_of_surjective {α : Type u} {β : Type v} [T : TopologicalSpace α] {f : β → α} (hf : Function.Surjective f) (a : β) :

Filter.map f (nhds a) = nhds (f a)

theorem isOpen_induced_eq {α : Type u_1} {β : Type u_2} [t : TopologicalSpace β] {f : α → β} {s : Set α} :

IsOpen s ↔ s ∈ Set.preimage f '' { s | IsOpen s }

theorem isOpen_induced {α : Type u_2} {β : Type u_1} [t : TopologicalSpace β] {f : α → β} {s : Set β} (h : IsOpen s) :

IsOpen (f ⁻¹' s)

theorem map_nhds_induced_eq {α : Type u_2} {β : Type u_1} [t : TopologicalSpace β] {f : α → β} (a : α) :

Filter.map f (nhds a) = nhdsWithin (f a) (Set.range f)

theorem map_nhds_induced_of_mem {α : Type u_2} {β : Type u_1} [t : TopologicalSpace β] {f : α → β} {a : α} (h : Set.range f ∈ nhds (f a)) :

Filter.map f (nhds a) = nhds (f a)

theorem closure_induced {α : Type u_2} {β : Type u_1} [t : TopologicalSpace β] {f : α → β} {a : α} {s : Set α} :

a ∈ closure s ↔ f a ∈ closure (f '' s)

theorem isClosed_induced_iff' {α : Type u_2} {β : Type u_1} [t : TopologicalSpace β] {f : α → β} {s : Set α} :

IsClosed s ↔ ∀ (a : α), f a ∈ closure (f '' s) → a ∈ s

@[simp]

theorem isOpen_singleton_true :

@[simp]

theorem nhds_true :

nhds True = pure True

@[simp]

theorem nhds_false :

nhds False = ⊤

theorem tendsto_nhds_true {α : Type u_1} {l : Filter α} {p : α → Prop} :

Filter.Tendsto p l (nhds True) ↔ Filter.Eventually (fun x => p x) l

theorem tendsto_nhds_Prop {α : Type u_1} {l : Filter α} {p : α → Prop} {q : Prop} :

Filter.Tendsto p l (nhds q) ↔ q → Filter.Eventually (fun x => p x) l

theorem continuous_Prop {α : Type u_1} [inst : TopologicalSpace α] {p : α → Prop} :

Continuous p ↔ IsOpen { x | p x }

theorem isOpen_iff_continuous_mem {α : Type u_1} [inst : TopologicalSpace α] {s : Set α} :

IsOpen s ↔ Continuous fun x => x ∈ s

theorem generateFrom_union {α : Type u} (a₁ : Set (Set α)) (a₂ : Set (Set α)) :

TopologicalSpace.generateFrom (a₁ ∪ a₂) = TopologicalSpace.generateFrom a₁ ⊓ TopologicalSpace.generateFrom a₂

theorem setOf_isOpen_sup {α : Type u} (t₁ : TopologicalSpace α) (t₂ : TopologicalSpace α) :

{ s | IsOpen s } = { s | IsOpen s } ∩ { s | IsOpen s }

theorem generateFrom_unionᵢ {α : Type u} {ι : Sort v} {f : ι → Set (Set α)} :

TopologicalSpace.generateFrom (Set.unionᵢ fun i => f i) = ⨅ i, TopologicalSpace.generateFrom (f i)

theorem setOf_isOpen_supᵢ {α : Type u} {ι : Sort v} {t : ι → TopologicalSpace α} :

{ s | IsOpen s } = Set.interᵢ fun i => { s | IsOpen s }

theorem generateFrom_unionₛ {α : Type u} {S : Set (Set (Set α))} :

TopologicalSpace.generateFrom (⋃₀ S) = ⨅ s, ⨅ h, TopologicalSpace.generateFrom s

theorem setOf_isOpen_supₛ {α : Type u} {T : Set (TopologicalSpace α)} :

{ s | IsOpen s } = Set.interᵢ fun t => Set.interᵢ fun h => { s | IsOpen s }

theorem generateFrom_union_isOpen {α : Type u} (a : TopologicalSpace α) (b : TopologicalSpace α) :

TopologicalSpace.generateFrom ({ s | IsOpen s } ∪ { s | IsOpen s }) = a ⊓ b

theorem generateFrom_unionᵢ_isOpen {α : Type u} {ι : Sort v} (f : ι → TopologicalSpace α) :

TopologicalSpace.generateFrom (Set.unionᵢ fun i => { s | IsOpen s }) = ⨅ i, f i

theorem generateFrom_inter {α : Type u} (a : TopologicalSpace α) (b : TopologicalSpace α) :

TopologicalSpace.generateFrom ({ s | IsOpen s } ∩ { s | IsOpen s }) = a ⊔ b

theorem generateFrom_interᵢ {α : Type u} {ι : Sort v} (f : ι → TopologicalSpace α) :

TopologicalSpace.generateFrom (Set.interᵢ fun i => { s | IsOpen s }) = ⨆ i, f i

theorem generateFrom_interᵢ_of_generateFrom_eq_self {α : Type u} {ι : Sort v} (f : ι → Set (Set α)) (hf : ∀ (i : ι), { s | IsOpen s } = f i) :

TopologicalSpace.generateFrom (Set.interᵢ fun i => f i) = ⨆ i, TopologicalSpace.generateFrom (f i)

theorem isOpen_supᵢ_iff {α : Type u} {ι : Sort v} {t : ι → TopologicalSpace α} {s : Set α} :

IsOpen s ↔ ∀ (i : ι), IsOpen s

theorem isClosed_supᵢ_iff {α : Type u} {ι : Sort v} {t : ι → TopologicalSpace α} {s : Set α} :

IsClosed s ↔ ∀ (i : ι), IsClosed s