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embedding.second_countable_topology [second_countable_topology β] (hf : embedding f) : second_countable_topology α
hf.1.second_countable_topology
lemma
embedding.second_countable_topology
topology
src/topology/bases.lean
[ "topology.constructions", "topology.continuous_on" ]
[ "embedding" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
topological_space (α : Type u)
(is_open : set α → Prop) (is_open_univ : is_open univ) (is_open_inter : ∀s t, is_open s → is_open t → is_open (s ∩ t)) (is_open_sUnion : ∀s, (∀t∈s, is_open t) → is_open (⋃₀ s))
class
topological_space
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "is_open_sUnion", "is_open_univ" ]
A topology on `α`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
topological_space.of_closed {α : Type u} (T : set (set α)) (empty_mem : ∅ ∈ T) (sInter_mem : ∀ A ⊆ T, ⋂₀ A ∈ T) (union_mem : ∀ A B ∈ T, A ∪ B ∈ T) : topological_space α
{ is_open := λ X, Xᶜ ∈ T, is_open_univ := by simp [empty_mem], is_open_inter := λ s t hs ht, by simpa only [compl_inter] using union_mem sᶜ hs tᶜ ht, is_open_sUnion := λ s hs, by rw set.compl_sUnion; exact sInter_mem (compl '' s) (λ z ⟨y, hy, hz⟩, by simpa [hz.symm] using hs y hy) }
def
topological_space.of_closed
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "is_open_sUnion", "is_open_univ", "set.compl_sUnion", "topological_space" ]
A constructor for topologies by specifying the closed sets, and showing that they satisfy the appropriate conditions.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open [topological_space α] (s : set α) : Prop
@topological_space.is_open _ ‹_› s
def
is_open
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "topological_space" ]
`is_open s` means that `s` is open in the ambient topological space on `α`
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_mk {p h₁ h₂ h₃} {s : set α} : is_open[⟨p, h₁, h₂, h₃⟩] s ↔ p s
iff.rfl
lemma
is_open_mk
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
topological_space_eq {f g : topological_space α} (h : is_open[f] = is_open[g]) : f = g
by unfreezingI { cases f, cases g, congr, exact h }
lemma
topological_space_eq
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "topological_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_univ : is_open (univ : set α)
topological_space.is_open_univ
lemma
is_open_univ
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open.inter (h₁ : is_open s₁) (h₂ : is_open s₂) : is_open (s₁ ∩ s₂)
topological_space.is_open_inter s₁ s₂ h₁ h₂
lemma
is_open.inter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_sUnion {s : set (set α)} (h : ∀t ∈ s, is_open t) : is_open (⋃₀ s)
topological_space.is_open_sUnion s h
lemma
is_open_sUnion
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
topological_space_eq_iff {t t' : topological_space α} : t = t' ↔ ∀ s, is_open[t] s ↔ is_open[t'] s
⟨λ h s, h ▸ iff.rfl, λ h, by { ext, exact h _ }⟩
lemma
topological_space_eq_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "topological_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_fold {s : set α} {t : topological_space α} : t.is_open s = is_open[t] s
rfl
lemma
is_open_fold
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "topological_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_Union {f : ι → set α} (h : ∀i, is_open (f i)) : is_open (⋃i, f i)
is_open_sUnion $ by rintro _ ⟨i, rfl⟩; exact h i
lemma
is_open_Union
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "is_open_sUnion" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_bUnion {s : set β} {f : β → set α} (h : ∀i∈s, is_open (f i)) : is_open (⋃i∈s, f i)
is_open_Union $ assume i, is_open_Union $ assume hi, h i hi
lemma
is_open_bUnion
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "is_open_Union" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open.union (h₁ : is_open s₁) (h₂ : is_open s₂) : is_open (s₁ ∪ s₂)
by rw union_eq_Union; exact is_open_Union (bool.forall_bool.2 ⟨h₂, h₁⟩)
lemma
is_open.union
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "is_open_Union" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_empty : is_open (∅ : set α)
by rw ← sUnion_empty; exact is_open_sUnion (assume a, false.elim)
lemma
is_open_empty
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "is_open_sUnion" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_sInter {s : set (set α)} (hs : s.finite) : (∀t ∈ s, is_open t) → is_open (⋂₀ s)
finite.induction_on hs (λ _, by rw sInter_empty; exact is_open_univ) $ λ a s has hs ih h, by rw sInter_insert; exact is_open.inter (h _ $ mem_insert _ _) (ih $ λ t, h t ∘ mem_insert_of_mem _)
lemma
is_open_sInter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "ih", "is_open", "is_open.inter", "is_open_univ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_bInter {s : set β} {f : β → set α} (hs : s.finite) : (∀i∈s, is_open (f i)) → is_open (⋂i∈s, f i)
finite.induction_on hs (λ _, by rw bInter_empty; exact is_open_univ) (λ a s has hs ih h, by rw bInter_insert; exact is_open.inter (h a (mem_insert _ _)) (ih (λ i hi, h i (mem_insert_of_mem _ hi))))
lemma
is_open_bInter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "ih", "is_open", "is_open.inter", "is_open_univ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_Inter [finite ι] {s : ι → set α} (h : ∀ i, is_open (s i)) : is_open (⋂ i, s i)
is_open_sInter (finite_range _) (forall_range_iff.2 h)
lemma
is_open_Inter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "finite", "is_open", "is_open_sInter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_bInter_finset {s : finset β} {f : β → set α} (h : ∀ i ∈ s, is_open (f i)) : is_open (⋂ i ∈ s, f i)
is_open_bInter (to_finite _) h
lemma
is_open_bInter_finset
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "finset", "is_open", "is_open_bInter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_const {p : Prop} : is_open {a : α | p}
by_cases (assume : p, begin simp only [this]; exact is_open_univ end) (assume : ¬ p, begin simp only [this]; exact is_open_empty end)
lemma
is_open_const
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "is_open_empty", "is_open_univ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open.and : is_open {a | p₁ a} → is_open {a | p₂ a} → is_open {a | p₁ a ∧ p₂ a}
is_open.inter
lemma
is_open.and
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "is_open.inter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed (s : set α) : Prop
(is_open_compl : is_open sᶜ)
class
is_closed
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open" ]
A set is closed if its complement is open
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_compl_iff {s : set α} : is_open sᶜ ↔ is_closed s
⟨λ h, ⟨h⟩, λ h, h.is_open_compl⟩
lemma
is_open_compl_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_empty : is_closed (∅ : set α)
by { rw [← is_open_compl_iff, compl_empty], exact is_open_univ }
lemma
is_closed_empty
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open_compl_iff", "is_open_univ" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_univ : is_closed (univ : set α)
by { rw [← is_open_compl_iff, compl_univ], exact is_open_empty }
lemma
is_closed_univ
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open_compl_iff", "is_open_empty" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed.union : is_closed s₁ → is_closed s₂ → is_closed (s₁ ∪ s₂)
λ h₁ h₂, by { rw [← is_open_compl_iff] at *, rw compl_union, exact is_open.inter h₁ h₂ }
lemma
is_closed.union
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open.inter", "is_open_compl_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_sInter {s : set (set α)} : (∀t ∈ s, is_closed t) → is_closed (⋂₀ s)
by simpa only [← is_open_compl_iff, compl_sInter, sUnion_image] using is_open_bUnion
lemma
is_closed_sInter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open_bUnion", "is_open_compl_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_Inter {f : ι → set α} (h : ∀i, is_closed (f i)) : is_closed (⋂i, f i )
is_closed_sInter $ assume t ⟨i, (heq : f i = t)⟩, heq ▸ h i
lemma
is_closed_Inter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_closed_sInter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_bInter {s : set β} {f : β → set α} (h : ∀ i ∈ s, is_closed (f i)) : is_closed (⋂ i ∈ s, f i)
is_closed_Inter $ λ i, is_closed_Inter $ h i
lemma
is_closed_bInter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_closed_Inter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_compl_iff {s : set α} : is_closed sᶜ ↔ is_open s
by rw [←is_open_compl_iff, compl_compl]
lemma
is_closed_compl_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "compl_compl", "is_closed", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open.is_closed_compl {s : set α} (hs : is_open s) : is_closed sᶜ
is_closed_compl_iff.2 hs
lemma
is_open.is_closed_compl
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open.sdiff {s t : set α} (h₁ : is_open s) (h₂ : is_closed t) : is_open (s \ t)
is_open.inter h₁ $ is_open_compl_iff.mpr h₂
lemma
is_open.sdiff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open", "is_open.inter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed.inter (h₁ : is_closed s₁) (h₂ : is_closed s₂) : is_closed (s₁ ∩ s₂)
by { rw [← is_open_compl_iff] at *, rw compl_inter, exact is_open.union h₁ h₂ }
lemma
is_closed.inter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open.union", "is_open_compl_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed.sdiff {s t : set α} (h₁ : is_closed s) (h₂ : is_open t) : is_closed (s \ t)
is_closed.inter h₁ (is_closed_compl_iff.mpr h₂)
lemma
is_closed.sdiff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_closed.inter", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_bUnion {s : set β} {f : β → set α} (hs : s.finite) : (∀i∈s, is_closed (f i)) → is_closed (⋃i∈s, f i)
finite.induction_on hs (λ _, by rw bUnion_empty; exact is_closed_empty) (λ a s has hs ih h, by rw bUnion_insert; exact is_closed.union (h a (mem_insert _ _)) (ih (λ i hi, h i (mem_insert_of_mem _ hi))))
lemma
is_closed_bUnion
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "ih", "is_closed", "is_closed.union", "is_closed_empty" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_Union [finite ι] {s : ι → set α} (h : ∀ i, is_closed (s i)) : is_closed (⋃ i, s i)
by { simp only [← is_open_compl_iff, compl_Union] at *, exact is_open_Inter h }
lemma
is_closed_Union
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "finite", "is_closed", "is_open_Inter", "is_open_compl_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_imp {p q : α → Prop} (hp : is_open {x | p x}) (hq : is_closed {x | q x}) : is_closed {x | p x → q x}
have {x | p x → q x} = {x | p x}ᶜ ∪ {x | q x}, from set.ext $ λ x, imp_iff_not_or, by rw [this]; exact is_closed.union (is_closed_compl_iff.mpr hp) hq
lemma
is_closed_imp
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "imp_iff_not_or", "is_closed", "is_closed.union", "is_open", "set.ext" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed.not : is_closed {a | p a} → is_open {a | ¬ p a}
is_open_compl_iff.mpr
lemma
is_closed.not
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior (s : set α) : set α
⋃₀ {t | is_open t ∧ t ⊆ s}
def
interior
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open" ]
The interior of a set `s` is the largest open subset of `s`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mem_interior {s : set α} {x : α} : x ∈ interior s ↔ ∃ t ⊆ s, is_open t ∧ x ∈ t
by simp only [interior, mem_sUnion, mem_set_of_eq, exists_prop, and_assoc, and.left_comm]
lemma
mem_interior
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "exists_prop", "interior", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_interior {s : set α} : is_open (interior s)
is_open_sUnion $ assume t ⟨h₁, h₂⟩, h₁
lemma
is_open_interior
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "is_open", "is_open_sUnion" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_subset {s : set α} : interior s ⊆ s
sUnion_subset $ assume t ⟨h₁, h₂⟩, h₂
lemma
interior_subset
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_maximal {s t : set α} (h₁ : t ⊆ s) (h₂ : is_open t) : t ⊆ interior s
subset_sUnion_of_mem ⟨h₂, h₁⟩
lemma
interior_maximal
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open.interior_eq {s : set α} (h : is_open s) : interior s = s
subset.antisymm interior_subset (interior_maximal (subset.refl s) h)
lemma
is_open.interior_eq
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_maximal", "interior_subset", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_eq_iff_is_open {s : set α} : interior s = s ↔ is_open s
⟨assume h, h ▸ is_open_interior, is_open.interior_eq⟩
lemma
interior_eq_iff_is_open
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "is_open", "is_open_interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
subset_interior_iff_is_open {s : set α} : s ⊆ interior s ↔ is_open s
by simp only [interior_eq_iff_is_open.symm, subset.antisymm_iff, interior_subset, true_and]
lemma
subset_interior_iff_is_open
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_subset", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open.subset_interior_iff {s t : set α} (h₁ : is_open s) : s ⊆ interior t ↔ s ⊆ t
⟨assume h, subset.trans h interior_subset, assume h₂, interior_maximal h₂ h₁⟩
lemma
is_open.subset_interior_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_maximal", "interior_subset", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
subset_interior_iff {s t : set α} : t ⊆ interior s ↔ ∃ U, is_open U ∧ t ⊆ U ∧ U ⊆ s
⟨λ h, ⟨interior s, is_open_interior, h, interior_subset⟩, λ ⟨U, hU, htU, hUs⟩, htU.trans (interior_maximal hUs hU)⟩
lemma
subset_interior_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_maximal", "is_open", "is_open_interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_mono {s t : set α} (h : s ⊆ t) : interior s ⊆ interior t
interior_maximal (subset.trans interior_subset h) is_open_interior
lemma
interior_mono
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_maximal", "interior_subset", "is_open_interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_empty : interior (∅ : set α) = ∅
is_open_empty.interior_eq
lemma
interior_empty
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_univ : interior (univ : set α) = univ
is_open_univ.interior_eq
lemma
interior_univ
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_eq_univ {s : set α} : interior s = univ ↔ s = univ
⟨λ h, univ_subset_iff.mp $ h.symm.trans_le interior_subset, λ h, h.symm ▸ interior_univ⟩
lemma
interior_eq_univ
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_subset" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_interior {s : set α} : interior (interior s) = interior s
is_open_interior.interior_eq
lemma
interior_interior
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_inter {s t : set α} : interior (s ∩ t) = interior s ∩ interior t
subset.antisymm (subset_inter (interior_mono $ inter_subset_left s t) (interior_mono $ inter_subset_right s t)) (interior_maximal (inter_subset_inter interior_subset interior_subset) $ is_open.inter is_open_interior is_open_interior)
lemma
interior_inter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_maximal", "interior_mono", "interior_subset", "is_open.inter", "is_open_interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
finset.interior_Inter {ι : Type*} (s : finset ι) (f : ι → set α) : interior (⋂ i ∈ s, f i) = ⋂ i ∈ s, interior (f i)
begin classical, refine s.induction_on (by simp) _, intros i s h₁ h₂, simp [h₂], end
lemma
finset.interior_Inter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "finset", "interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_Inter {ι : Type*} [finite ι] (f : ι → set α) : interior (⋂ i, f i) = ⋂ i, interior (f i)
by { casesI nonempty_fintype ι, convert finset.univ.interior_Inter f; simp }
lemma
interior_Inter
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "finite", "interior", "nonempty_fintype" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_union_is_closed_of_interior_empty {s t : set α} (h₁ : is_closed s) (h₂ : interior t = ∅) : interior (s ∪ t) = interior s
have interior (s ∪ t) ⊆ s, from assume x ⟨u, ⟨(hu₁ : is_open u), (hu₂ : u ⊆ s ∪ t)⟩, (hx₁ : x ∈ u)⟩, classical.by_contradiction $ assume hx₂ : x ∉ s, have u \ s ⊆ t, from assume x ⟨h₁, h₂⟩, or.resolve_left (hu₂ h₁) h₂, have u \ s ⊆ interior t, by rwa (is_open.sdiff hu₁ h₁).subset_interior_iff, ...
lemma
interior_union_is_closed_of_interior_empty
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_maximal", "interior_mono", "is_closed", "is_open", "is_open.sdiff", "is_open_interior", "subset_interior_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_open_iff_forall_mem_open : is_open s ↔ ∀ x ∈ s, ∃ t ⊆ s, is_open t ∧ x ∈ t
by rw ← subset_interior_iff_is_open; simp only [subset_def, mem_interior]
lemma
is_open_iff_forall_mem_open
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_open", "mem_interior", "subset_interior_iff_is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_Inter_subset (s : ι → set α) : interior (⋂ i, s i) ⊆ ⋂ i, interior (s i)
subset_Inter $ λ i, interior_mono $ Inter_subset _ _
lemma
interior_Inter_subset
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_mono" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_Inter₂_subset (p : ι → Sort*) (s : Π i, p i → set α) : interior (⋂ i j, s i j) ⊆ ⋂ i j, interior (s i j)
(interior_Inter_subset _).trans $ Inter_mono $ λ i, interior_Inter_subset _
lemma
interior_Inter₂_subset
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_Inter_subset" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_sInter_subset (S : set (set α)) : interior (⋂₀ S) ⊆ ⋂ s ∈ S, interior s
calc interior (⋂₀ S) = interior (⋂ s ∈ S, s) : by rw sInter_eq_bInter ... ⊆ ⋂ s ∈ S, interior s : interior_Inter₂_subset _ _
lemma
interior_sInter_subset
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "interior", "interior_Inter₂_subset" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure (s : set α) : set α
⋂₀ {t | is_closed t ∧ s ⊆ t}
def
closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "is_closed" ]
The closure of `s` is the smallest closed set containing `s`.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_closure {s : set α} : is_closed (closure s)
is_closed_sInter $ assume t ⟨h₁, h₂⟩, h₁
lemma
is_closed_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "is_closed", "is_closed_sInter" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
subset_closure {s : set α} : s ⊆ closure s
subset_sInter $ assume t ⟨h₁, h₂⟩, h₂
lemma
subset_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
not_mem_of_not_mem_closure {s : set α} {P : α} (hP : P ∉ closure s) : P ∉ s
λ h, hP (subset_closure h)
lemma
not_mem_of_not_mem_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_minimal {s t : set α} (h₁ : s ⊆ t) (h₂ : is_closed t) : closure s ⊆ t
sInter_subset_of_mem ⟨h₂, h₁⟩
lemma
closure_minimal
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "is_closed" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
disjoint.closure_left {s t : set α} (hd : disjoint s t) (ht : is_open t) : disjoint (closure s) t
disjoint_compl_left.mono_left $ closure_minimal hd.subset_compl_right ht.is_closed_compl
lemma
disjoint.closure_left
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_minimal", "disjoint", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
disjoint.closure_right {s t : set α} (hd : disjoint s t) (hs : is_open s) : disjoint s (closure t)
(hd.symm.closure_left hs).symm
lemma
disjoint.closure_right
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "disjoint", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed.closure_eq {s : set α} (h : is_closed s) : closure s = s
subset.antisymm (closure_minimal (subset.refl s) h) subset_closure
lemma
is_closed.closure_eq
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_minimal", "is_closed", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed.closure_subset {s : set α} (hs : is_closed s) : closure s ⊆ s
closure_minimal (subset.refl _) hs
lemma
is_closed.closure_subset
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_minimal", "is_closed" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed.closure_subset_iff {s t : set α} (h₁ : is_closed t) : closure s ⊆ t ↔ s ⊆ t
⟨subset.trans subset_closure, assume h, closure_minimal h h₁⟩
lemma
is_closed.closure_subset_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_minimal", "is_closed", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed.mem_iff_closure_subset {s : set α} (hs : is_closed s) {x : α} : x ∈ s ↔ closure ({x} : set α) ⊆ s
(hs.closure_subset_iff.trans set.singleton_subset_iff).symm
lemma
is_closed.mem_iff_closure_subset
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "is_closed", "set.singleton_subset_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_mono {s t : set α} (h : s ⊆ t) : closure s ⊆ closure t
closure_minimal (subset.trans h subset_closure) is_closed_closure
lemma
closure_mono
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_minimal", "is_closed_closure", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
monotone_closure (α : Type*) [topological_space α] : monotone (@closure α _)
λ _ _, closure_mono
lemma
monotone_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_mono", "monotone", "topological_space" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
diff_subset_closure_iff {s t : set α} : s \ t ⊆ closure t ↔ s ⊆ closure t
by rw [diff_subset_iff, union_eq_self_of_subset_left subset_closure]
lemma
diff_subset_closure_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_inter_subset_inter_closure (s t : set α) : closure (s ∩ t) ⊆ closure s ∩ closure t
(monotone_closure α).map_inf_le s t
lemma
closure_inter_subset_inter_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "monotone_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
is_closed_of_closure_subset {s : set α} (h : closure s ⊆ s) : is_closed s
by rw subset.antisymm subset_closure h; exact is_closed_closure
lemma
is_closed_of_closure_subset
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "is_closed", "is_closed_closure", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_eq_iff_is_closed {s : set α} : closure s = s ↔ is_closed s
⟨assume h, h ▸ is_closed_closure, is_closed.closure_eq⟩
lemma
closure_eq_iff_is_closed
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "is_closed", "is_closed_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_subset_iff_is_closed {s : set α} : closure s ⊆ s ↔ is_closed s
⟨is_closed_of_closure_subset, is_closed.closure_subset⟩
lemma
closure_subset_iff_is_closed
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "is_closed" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_empty : closure (∅ : set α) = ∅
is_closed_empty.closure_eq
lemma
closure_empty
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_empty_iff (s : set α) : closure s = ∅ ↔ s = ∅
⟨subset_eq_empty subset_closure, λ h, h.symm ▸ closure_empty⟩
lemma
closure_empty_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_nonempty_iff {s : set α} : (closure s).nonempty ↔ s.nonempty
by simp only [nonempty_iff_ne_empty, ne.def, closure_empty_iff]
lemma
closure_nonempty_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_empty_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_univ : closure (univ : set α) = univ
is_closed_univ.closure_eq
lemma
closure_univ
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_closure {s : set α} : closure (closure s) = closure s
is_closed_closure.closure_eq
lemma
closure_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_union {s t : set α} : closure (s ∪ t) = closure s ∪ closure t
subset.antisymm (closure_minimal (union_subset_union subset_closure subset_closure) $ is_closed.union is_closed_closure is_closed_closure) ((monotone_closure α).le_map_sup s t)
lemma
closure_union
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_minimal", "is_closed.union", "is_closed_closure", "monotone_closure", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
finset.closure_bUnion {ι : Type*} (s : finset ι) (f : ι → set α) : closure (⋃ i ∈ s, f i) = ⋃ i ∈ s, closure (f i)
begin classical, refine s.induction_on (by simp) _, intros i s h₁ h₂, simp [h₂], end
lemma
finset.closure_bUnion
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "finset" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_Union {ι : Type*} [finite ι] (f : ι → set α) : closure (⋃ i, f i) = ⋃ i, closure (f i)
by { casesI nonempty_fintype ι, convert finset.univ.closure_bUnion f; simp }
lemma
closure_Union
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "finite", "nonempty_fintype" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_subset_closure {s : set α} : interior s ⊆ closure s
subset.trans interior_subset subset_closure
lemma
interior_subset_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "interior", "interior_subset", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_eq_compl_interior_compl {s : set α} : closure s = (interior sᶜ)ᶜ
begin rw [interior, closure, compl_sUnion, compl_image_set_of], simp only [compl_subset_compl, is_open_compl_iff], end
lemma
closure_eq_compl_interior_compl
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "interior", "is_open_compl_iff" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
interior_compl {s : set α} : interior sᶜ = (closure s)ᶜ
by simp [closure_eq_compl_interior_compl]
lemma
interior_compl
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_eq_compl_interior_compl", "interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_compl {s : set α} : closure sᶜ = (interior s)ᶜ
by simp [closure_eq_compl_interior_compl]
lemma
closure_compl
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_eq_compl_interior_compl", "interior" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
mem_closure_iff {s : set α} {a : α} : a ∈ closure s ↔ ∀ o, is_open o → a ∈ o → (o ∩ s).nonempty
⟨λ h o oo ao, classical.by_contradiction $ λ os, have s ⊆ oᶜ, from λ x xs xo, os ⟨x, xo, xs⟩, closure_minimal this (is_closed_compl_iff.2 oo) h ao, λ H c ⟨h₁, h₂⟩, classical.by_contradiction $ λ nc, let ⟨x, hc, hs⟩ := (H _ h₁.is_open_compl nc) in hc (h₂ hs)⟩
theorem
mem_closure_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "closure_minimal", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
closure_inter_open_nonempty_iff {s t : set α} (h : is_open t) : (closure s ∩ t).nonempty ↔ (s ∩ t).nonempty
⟨λ ⟨x, hxcs, hxt⟩, inter_comm t s ▸ mem_closure_iff.1 hxcs t h hxt, λ h, h.mono $ inf_le_inf_right t subset_closure⟩
lemma
closure_inter_open_nonempty_iff
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "inf_le_inf_right", "is_open" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
filter.le_lift'_closure (l : filter α) : l ≤ l.lift' closure
le_lift'.2 $ λ s hs, mem_of_superset hs subset_closure
lemma
filter.le_lift'_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "filter", "subset_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
filter.has_basis.lift'_closure {l : filter α} {p : ι → Prop} {s : ι → set α} (h : l.has_basis p s) : (l.lift' closure).has_basis p (λ i, closure (s i))
h.lift' (monotone_closure α)
lemma
filter.has_basis.lift'_closure
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "filter", "monotone_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
filter.has_basis.lift'_closure_eq_self {l : filter α} {p : ι → Prop} {s : ι → set α} (h : l.has_basis p s) (hc : ∀ i, p i → is_closed (s i)) : l.lift' closure = l
le_antisymm (h.ge_iff.2 $ λ i hi, (hc i hi).closure_eq ▸ mem_lift' (h.mem_of_mem hi)) l.le_lift'_closure
lemma
filter.has_basis.lift'_closure_eq_self
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "filter", "is_closed" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
filter.lift'_closure_eq_bot {l : filter α} : l.lift' closure = ⊥ ↔ l = ⊥
⟨λ h, bot_unique $ h ▸ l.le_lift'_closure, λ h, h.symm ▸ by rw [lift'_bot (monotone_closure _), closure_empty, principal_empty]⟩
lemma
filter.lift'_closure_eq_bot
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "bot_unique", "closure", "closure_empty", "filter", "monotone_closure" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
dense (s : set α) : Prop
∀ x, x ∈ closure s
def
dense
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure" ]
A set is dense in a topological space if every point belongs to its closure.
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
dense_iff_closure_eq {s : set α} : dense s ↔ closure s = univ
eq_univ_iff_forall.symm
lemma
dense_iff_closure_eq
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "dense" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83
dense.closure_eq {s : set α} (h : dense s) : closure s = univ
dense_iff_closure_eq.mp h
lemma
dense.closure_eq
topology
src/topology/basic.lean
[ "order.filter.ultrafilter", "algebra.support", "order.filter.lift" ]
[ "closure", "dense" ]
https://github.com/leanprover-community/mathlib
65a1391a0106c9204fe45bc73a039f056558cb83