Topological properties of ℝ #
Equations
- One or more equations did not get rendered due to their size.
Equations
theorem
Real.isTopologicalBasis_Ioo_rat :
TopologicalSpace.IsTopologicalBasis (⋃ (a : ℚ), ⋃ (b : ℚ), ⋃ (_ : a < b), {Set.Ioo ↑a ↑b})
@[deprecated cocompact_eq_atBot_atTop]
theorem
Real.cocompact_eq
{α : Type u_2}
[LinearOrder α]
[TopologicalSpace α]
[NoMaxOrder α]
[NoMinOrder α]
[OrderClosedTopology α]
[CompactIccSpace α]
:
Filter.cocompact α = Filter.atBot ⊔ Filter.atTop
Alias of cocompact_eq_atBot_atTop
.
@[deprecated atBot_le_cocompact]
theorem
Real.atBot_le_cocompact
{α : Type u_2}
[LinearOrder α]
[TopologicalSpace α]
[NoMinOrder α]
[ClosedIicTopology α]
:
Filter.atBot ≤ Filter.cocompact α
Alias of atBot_le_cocompact
.
@[deprecated atTop_le_cocompact]
theorem
Real.atTop_le_cocompact
{α : Type u_2}
[LinearOrder α]
[TopologicalSpace α]
[NoMaxOrder α]
[ClosedIciTopology α]
:
Filter.atTop ≤ Filter.cocompact α
Alias of atTop_le_cocompact
.
theorem
Real.uniformContinuous_inv
(s : Set ℝ)
{r : ℝ}
(r0 : 0 < r)
(H : ∀ x ∈ s, r ≤ |x|)
:
UniformContinuous fun (p : ↑s) => (↑p)⁻¹
@[deprecated HasContinuousInv₀.continuousAt_inv₀]
@[deprecated Continuous.inv₀]
theorem
Real.Continuous.inv
{α : Type u}
[TopologicalSpace α]
{f : α → ℝ}
(h : ∀ (a : α), f a ≠ 0)
(hf : Continuous f)
:
Continuous fun (a : α) => (f a)⁻¹
@[deprecated continuous_mul]
theorem
Real.isBounded_iff_bddBelow_bddAbove
{s : Set ℝ}
:
Bornology.IsBounded s ↔ BddBelow s ∧ BddAbove s
theorem
Function.Periodic.compact_of_continuous
{α : Type u}
[TopologicalSpace α]
{f : ℝ → α}
{c : ℝ}
(hp : Function.Periodic f c)
(hc : c ≠ 0)
(hf : Continuous f)
:
A continuous, periodic function has compact range.
@[deprecated Function.Periodic.compact_of_continuous]
theorem
Function.Periodic.compact_of_continuous'
{α : Type u}
[TopologicalSpace α]
{f : ℝ → α}
{c : ℝ}
(hp : Function.Periodic f c)
(hc : 0 < c)
(hf : Continuous f)
:
theorem
Function.Periodic.isBounded_of_continuous
{α : Type u}
[PseudoMetricSpace α]
{f : ℝ → α}
{c : ℝ}
(hp : Function.Periodic f c)
(hc : c ≠ 0)
(hf : Continuous f)
:
A continuous, periodic function is bounded.
instance
Int.instDiscreteTopologySubtypeRealMemAddSubgroupInstAddGroupRealInstMembershipInstSetLikeAddSubgroupZmultiplesInstTopologicalSpaceSubtypeToTopologicalSpaceToUniformSpacePseudoMetricSpace
{a : ℝ}
:
This is a special case of NormedSpace.discreteTopology_zmultiples
. It exists only to simplify
dependencies.
Equations
- ⋯ = ⋯
Under the coercion from ℤ
to ℝ
, inverse images of compact sets are finite.
theorem
Int.tendsto_zmultiplesHom_cofinite
{a : ℝ}
(ha : a ≠ 0)
:
Filter.Tendsto (⇑((zmultiplesHom ℝ) a)) Filter.cofinite (Filter.cocompact ℝ)
For nonzero a
, the "multiples of a
" map zmultiplesHom
from ℤ
to ℝ
is discrete, i.e.
inverse images of compact sets are finite.
theorem
AddSubgroup.tendsto_zmultiples_subtype_cofinite
(a : ℝ)
:
Filter.Tendsto (⇑(AddSubgroup.subtype (AddSubgroup.zmultiples a))) Filter.cofinite (Filter.cocompact ℝ)
The subgroup "multiples of a
" (zmultiples a
) is a discrete subgroup of ℝ
, i.e. its
intersection with compact sets is finite.