Documentation

Mathlib.Topology.Order.IsLUB

Properties of LUB and GLB in an order topology #

theorem IsLUB.frequently_mem {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsLUB s a) (hs : s.Nonempty) :
∃ᶠ (x : α) in nhdsWithin a (Set.Iic a), x ∈ s
theorem IsLUB.frequently_nhds_mem {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsLUB s a) (hs : s.Nonempty) :
∃ᶠ (x : α) in nhds a, x ∈ s
theorem IsGLB.frequently_mem {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsGLB s a) (hs : s.Nonempty) :
∃ᶠ (x : α) in nhdsWithin a (Set.Ici a), x ∈ s
theorem IsGLB.frequently_nhds_mem {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsGLB s a) (hs : s.Nonempty) :
∃ᶠ (x : α) in nhds a, x ∈ s
theorem IsLUB.mem_closure {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsLUB s a) (hs : s.Nonempty) :
theorem IsGLB.mem_closure {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsGLB s a) (hs : s.Nonempty) :
theorem IsLUB.nhdsWithin_neBot {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsLUB s a) (hs : s.Nonempty) :
theorem IsGLB.nhdsWithin_neBot {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsGLB s a) (hs : s.Nonempty) :
theorem isLUB_of_mem_nhds {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {s : Set α} {a : α} {f : Filter α} (hsa : a ∈ upperBounds s) (hsf : s ∈ f) [(f ⊓ nhds a).NeBot] :
IsLUB s a
theorem isLUB_of_mem_closure {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {s : Set α} {a : α} (hsa : a ∈ upperBounds s) (hsf : a ∈ closure s) :
IsLUB s a
theorem isGLB_of_mem_nhds {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {s : Set α} {a : α} {f : Filter α} (hsa : a ∈ lowerBounds s) (hsf : s ∈ f) [(f ⊓ nhds a).NeBot] :
IsGLB s a
theorem isGLB_of_mem_closure {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {s : Set α} {a : α} (hsa : a ∈ lowerBounds s) (hsf : a ∈ closure s) :
IsGLB s a
theorem IsLUB.mem_upperBounds_of_tendsto {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [Preorder γ] [TopologicalSpace γ] [OrderClosedTopology γ] {f : α → γ} {s : Set α} {a : α} {b : γ} (hf : MonotoneOn f s) (ha : IsLUB s a) (hb : Filter.Tendsto f (nhdsWithin a s) (nhds b)) :
theorem IsLUB.isLUB_of_tendsto {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [Preorder γ] [TopologicalSpace γ] [OrderClosedTopology γ] {f : α → γ} {s : Set α} {a : α} {b : γ} (hf : MonotoneOn f s) (ha : IsLUB s a) (hs : s.Nonempty) (hb : Filter.Tendsto f (nhdsWithin a s) (nhds b)) :
IsLUB (f '' s) b
theorem IsGLB.mem_lowerBounds_of_tendsto {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [Preorder γ] [TopologicalSpace γ] [OrderClosedTopology γ] {f : α → γ} {s : Set α} {a : α} {b : γ} (hf : MonotoneOn f s) (ha : IsGLB s a) (hb : Filter.Tendsto f (nhdsWithin a s) (nhds b)) :
theorem IsGLB.isGLB_of_tendsto {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [Preorder γ] [TopologicalSpace γ] [OrderClosedTopology γ] {f : α → γ} {s : Set α} {a : α} {b : γ} (hf : MonotoneOn f s) :
IsGLB s a → s.Nonempty → Filter.Tendsto f (nhdsWithin a s) (nhds b) → IsGLB (f '' s) b
theorem IsLUB.mem_lowerBounds_of_tendsto {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [Preorder γ] [TopologicalSpace γ] [OrderClosedTopology γ] {f : α → γ} {s : Set α} {a : α} {b : γ} (hf : AntitoneOn f s) (ha : IsLUB s a) (hb : Filter.Tendsto f (nhdsWithin a s) (nhds b)) :
theorem IsLUB.isGLB_of_tendsto {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [Preorder γ] [TopologicalSpace γ] [OrderClosedTopology γ] {f : α → γ} {s : Set α} {a : α} {b : γ} (hf : AntitoneOn f s) (ha : IsLUB s a) (hs : s.Nonempty) (hb : Filter.Tendsto f (nhdsWithin a s) (nhds b)) :
IsGLB (f '' s) b
theorem IsGLB.mem_upperBounds_of_tendsto {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [Preorder γ] [TopologicalSpace γ] [OrderClosedTopology γ] {f : α → γ} {s : Set α} {a : α} {b : γ} (hf : AntitoneOn f s) (ha : IsGLB s a) (hb : Filter.Tendsto f (nhdsWithin a s) (nhds b)) :
theorem IsGLB.isLUB_of_tendsto {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [Preorder γ] [TopologicalSpace γ] [OrderClosedTopology γ] {f : α → γ} {s : Set α} {a : α} {b : γ} (hf : AntitoneOn f s) (ha : IsGLB s a) (hs : s.Nonempty) (hb : Filter.Tendsto f (nhdsWithin a s) (nhds b)) :
IsLUB (f '' s) b
theorem IsLUB.mem_of_isClosed {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsLUB s a) (hs : s.Nonempty) (sc : IsClosed s) :
a ∈ s
theorem IsClosed.isLUB_mem {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsLUB s a) (hs : s.Nonempty) (sc : IsClosed s) :
a ∈ s

Alias of IsLUB.mem_of_isClosed.

theorem IsGLB.mem_of_isClosed {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsGLB s a) (hs : s.Nonempty) (sc : IsClosed s) :
a ∈ s
theorem IsClosed.isGLB_mem {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {a : α} {s : Set α} (ha : IsGLB s a) (hs : s.Nonempty) (sc : IsClosed s) :
a ∈ s

Alias of IsGLB.mem_of_isClosed.

theorem isLUB_iff_of_subset_of_subset_closure {α : Type u_3} [TopologicalSpace α] [Preorder α] [ClosedIicTopology α] {s t : Set α} (hst : s ⊆ t) (hts : t ⊆ closure s) {x : α} :
IsLUB s x ↔ IsLUB t x
theorem isGLB_iff_of_subset_of_subset_closure {α : Type u_3} [TopologicalSpace α] [Preorder α] [ClosedIciTopology α] {s t : Set α} (hst : s ⊆ t) (hts : t ⊆ closure s) {x : α} :
IsGLB s x ↔ IsGLB t x
theorem Dense.isLUB_inter_iff {α : Type u_3} [TopologicalSpace α] [Preorder α] [ClosedIicTopology α] {s t : Set α} (hs : Dense s) (ht : IsOpen t) {x : α} :
IsLUB (t ∩ s) x ↔ IsLUB t x
theorem Dense.isGLB_inter_iff {α : Type u_3} [TopologicalSpace α] [Preorder α] [ClosedIciTopology α] {s t : Set α} (hs : Dense s) (ht : IsOpen t) {x : α} :
IsGLB (t ∩ s) x ↔ IsGLB t x
theorem Dense.upperBounds_image {γ : Type u_2} {α : Type u_3} [TopologicalSpace α] [Preorder α] [ClosedIicTopology α] {f : γ → α} [TopologicalSpace γ] {S : Set γ} (hS : Dense S) (hf : Continuous f) :

The upper bounds of the image of a continuous function on a dense set are equal to the upper bounds of the range of the universe.

theorem Dense.lowerBounds_image {γ : Type u_2} {α : Type u_3} [TopologicalSpace α] [Preorder α] [ClosedIciTopology α] {f : γ → α} [TopologicalSpace γ] {S : Set γ} (hS : Dense S) (hf : Continuous f) :

The lower bounds of the image of a continuous function on a dense set are equal to the lower bounds of the range of the universe.

theorem Dense.ciSup {γ : Type u_2} {α : Type u_3} [TopologicalSpace α] [ConditionallyCompleteLattice α] [ClosedIicTopology α] {f : γ → α} [TopologicalSpace γ] {S : Set γ} (hS : Dense S) (hf : Continuous f) (h : BddAbove (Set.range f)) :
⨆ (s : ↑S), f ↑s = ⨆ (i : γ), f i

The supremum of a bounded above, continuous function on a dense set is equal to the supremum on the universe.

theorem Dense.ciInf {γ : Type u_2} {α : Type u_3} [TopologicalSpace α] [ConditionallyCompleteLattice α] [ClosedIciTopology α] {f : γ → α} [TopologicalSpace γ] {S : Set γ} (hS : Dense S) (hf : Continuous f) (h : BddBelow (Set.range f)) :
⨅ (s : ↑S), f ↑s = ⨅ (i : γ), f i

The infimum of a bounded below, continuous function on a dense set is equal to the infimum on the universe.

theorem Dense.ciSup' {γ : Type u_2} {α : Type u_3} [TopologicalSpace α] [ConditionallyCompleteLinearOrder α] [ClosedIicTopology α] {f : γ → α} [TopologicalSpace γ] {S : Set γ} (hS : Dense S) (hf : Continuous f) :
⨆ (s : ↑S), f ↑s = ⨆ (i : γ), f i

This is an analogue of Dense.continuous_sup for functions taking values in a conditionally complete linear order. The assumption of BddAbove (range f) is not needed in this theorem.

theorem Dense.ciInf' {γ : Type u_2} {α : Type u_3} [TopologicalSpace α] [ConditionallyCompleteLinearOrder α] [ClosedIciTopology α] {f : γ → α} [TopologicalSpace γ] {S : Set γ} (hS : Dense S) (hf : Continuous f) :
⨅ (s : ↑S), f ↑s = ⨅ (i : γ), f i

This is an analogue of Dense.continuous_inf for functions taking values in a conditionally complete linear order. The assumption of BddBelow (range f) is not needed in this theorem.

A closed interval in a conditionally complete linear order is compact. Also see general API on CompactIccSpace.

theorem upperClosure_eq_Ici_csInf {α : Type u_3} [ConditionallyCompleteLinearOrder α] [TopologicalSpace α] [OrderTopology α] {s : Set α} (h₁ : s.Nonempty) (h₂ : BddBelow s) (hs : IsClosed s) :
theorem lowerClosure_eq_Iic_csSup {α : Type u_3} [ConditionallyCompleteLinearOrder α] [TopologicalSpace α] [OrderTopology α] {s : Set α} (h₁ : s.Nonempty) (h₂ : BddAbove s) (hs : IsClosed s) :

Existence of sequences tending to sInf or sSup of a given set #

theorem IsLUB.exists_seq_strictMono_tendsto_of_notMem {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {t : Set α} {x : α} [(nhds x).IsCountablyGenerated] (htx : IsLUB t x) (notMem : x ∉ t) (ht : t.Nonempty) :
∃ (u : ℕ → α), StrictMono u ∧ (∀ (n : ℕ), u n < x) ∧ Filter.Tendsto u Filter.atTop (nhds x) ∧ ∀ (n : ℕ), u n ∈ t
theorem IsLUB.exists_seq_monotone_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {t : Set α} {x : α} [(nhds x).IsCountablyGenerated] (htx : IsLUB t x) (ht : t.Nonempty) :
∃ (u : ℕ → α), Monotone u ∧ (∀ (n : ℕ), u n ≤ x) ∧ Filter.Tendsto u Filter.atTop (nhds x) ∧ ∀ (n : ℕ), u n ∈ t
theorem exists_seq_strictMono_tendsto' {α : Type u_3} [LinearOrder α] [TopologicalSpace α] [DenselyOrdered α] [OrderTopology α] [FirstCountableTopology α] {x y : α} (hy : y < x) :
∃ (u : ℕ → α), StrictMono u ∧ (∀ (n : ℕ), u n ∈ Set.Ioo y x) ∧ Filter.Tendsto u Filter.atTop (nhds x)
theorem exists_seq_strictMono_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [DenselyOrdered α] [NoMinOrder α] [FirstCountableTopology α] (x : α) :
∃ (u : ℕ → α), StrictMono u ∧ (∀ (n : ℕ), u n < x) ∧ Filter.Tendsto u Filter.atTop (nhds x)
theorem exists_seq_tendsto_sSup {α : Type u_3} [ConditionallyCompleteLinearOrder α] [TopologicalSpace α] [OrderTopology α] [FirstCountableTopology α] {S : Set α} (hS : S.Nonempty) (hS' : BddAbove S) :
∃ (u : ℕ → α), Monotone u ∧ Filter.Tendsto u Filter.atTop (nhds (sSup S)) ∧ ∀ (n : ℕ), u n ∈ S
theorem Dense.exists_seq_strictMono_tendsto_of_lt {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [DenselyOrdered α] [FirstCountableTopology α] {s : Set α} (hs : Dense s) {x y : α} (hy : y < x) :
∃ (u : ℕ → α), StrictMono u ∧ (∀ (n : ℕ), u n ∈ Set.Ioo y x ∩ s) ∧ Filter.Tendsto u Filter.atTop (nhds x)
theorem Dense.exists_seq_strictMono_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [DenselyOrdered α] [NoMinOrder α] [FirstCountableTopology α] {s : Set α} (hs : Dense s) (x : α) :
∃ (u : ℕ → α), StrictMono u ∧ (∀ (n : ℕ), u n ∈ Set.Iio x ∩ s) ∧ Filter.Tendsto u Filter.atTop (nhds x)
theorem DenseRange.exists_seq_strictMono_tendsto_of_lt {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {β : Type u_3} [LinearOrder β] [DenselyOrdered α] [FirstCountableTopology α] {f : β → α} {x y : α} (hf : DenseRange f) (hmono : Monotone f) (hlt : y < x) :
∃ (u : ℕ → β), StrictMono u ∧ (∀ (n : ℕ), f (u n) ∈ Set.Ioo y x) ∧ Filter.Tendsto (f ∘ u) Filter.atTop (nhds x)
theorem DenseRange.exists_seq_strictMono_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {β : Type u_3} [LinearOrder β] [DenselyOrdered α] [NoMinOrder α] [FirstCountableTopology α] {f : β → α} (hf : DenseRange f) (hmono : Monotone f) (x : α) :
∃ (u : ℕ → β), StrictMono u ∧ (∀ (n : ℕ), f (u n) ∈ Set.Iio x) ∧ Filter.Tendsto (f ∘ u) Filter.atTop (nhds x)
theorem IsGLB.exists_seq_strictAnti_tendsto_of_notMem {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {t : Set α} {x : α} [(nhds x).IsCountablyGenerated] (htx : IsGLB t x) (notMem : x ∉ t) (ht : t.Nonempty) :
∃ (u : ℕ → α), StrictAnti u ∧ (∀ (n : ℕ), x < u n) ∧ Filter.Tendsto u Filter.atTop (nhds x) ∧ ∀ (n : ℕ), u n ∈ t
theorem IsGLB.exists_seq_antitone_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {t : Set α} {x : α} [(nhds x).IsCountablyGenerated] (htx : IsGLB t x) (ht : t.Nonempty) :
∃ (u : ℕ → α), Antitone u ∧ (∀ (n : ℕ), x ≤ u n) ∧ Filter.Tendsto u Filter.atTop (nhds x) ∧ ∀ (n : ℕ), u n ∈ t
theorem exists_seq_strictAnti_tendsto' {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [DenselyOrdered α] [FirstCountableTopology α] {x y : α} (hy : x < y) :
∃ (u : ℕ → α), StrictAnti u ∧ (∀ (n : ℕ), u n ∈ Set.Ioo x y) ∧ Filter.Tendsto u Filter.atTop (nhds x)
theorem exists_seq_strictAnti_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [DenselyOrdered α] [NoMaxOrder α] [FirstCountableTopology α] (x : α) :
∃ (u : ℕ → α), StrictAnti u ∧ (∀ (n : ℕ), x < u n) ∧ Filter.Tendsto u Filter.atTop (nhds x)
theorem exists_seq_strictAnti_strictMono_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [DenselyOrdered α] [FirstCountableTopology α] {x y : α} (h : x < y) :
∃ (u : ℕ → α) (v : ℕ → α), StrictAnti u ∧ StrictMono v ∧ (∀ (k : ℕ), u k ∈ Set.Ioo x y) ∧ (∀ (l : ℕ), v l ∈ Set.Ioo x y) ∧ (∀ (k l : ℕ), u k < v l) ∧ Filter.Tendsto u Filter.atTop (nhds x) ∧ Filter.Tendsto v Filter.atTop (nhds y)
theorem exists_seq_tendsto_sInf {α : Type u_3} [ConditionallyCompleteLinearOrder α] [TopologicalSpace α] [OrderTopology α] [FirstCountableTopology α] {S : Set α} (hS : S.Nonempty) (hS' : BddBelow S) :
∃ (u : ℕ → α), Antitone u ∧ Filter.Tendsto u Filter.atTop (nhds (sInf S)) ∧ ∀ (n : ℕ), u n ∈ S
theorem Dense.exists_seq_strictAnti_tendsto_of_lt {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [DenselyOrdered α] [FirstCountableTopology α] {s : Set α} (hs : Dense s) {x y : α} (hy : x < y) :
∃ (u : ℕ → α), StrictAnti u ∧ (∀ (n : ℕ), u n ∈ Set.Ioo x y ∩ s) ∧ Filter.Tendsto u Filter.atTop (nhds x)
theorem Dense.exists_seq_strictAnti_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [DenselyOrdered α] [NoMaxOrder α] [FirstCountableTopology α] {s : Set α} (hs : Dense s) (x : α) :
∃ (u : ℕ → α), StrictAnti u ∧ (∀ (n : ℕ), u n ∈ Set.Ioi x ∩ s) ∧ Filter.Tendsto u Filter.atTop (nhds x)
theorem DenseRange.exists_seq_strictAnti_tendsto_of_lt {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {β : Type u_3} [LinearOrder β] [DenselyOrdered α] [FirstCountableTopology α] {f : β → α} {x y : α} (hf : DenseRange f) (hmono : Monotone f) (hlt : x < y) :
∃ (u : ℕ → β), StrictAnti u ∧ (∀ (n : ℕ), f (u n) ∈ Set.Ioo x y) ∧ Filter.Tendsto (f ∘ u) Filter.atTop (nhds x)
theorem DenseRange.exists_seq_strictAnti_tendsto {α : Type u_1} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] {β : Type u_3} [LinearOrder β] [DenselyOrdered α] [NoMaxOrder α] [FirstCountableTopology α] {f : β → α} (hf : DenseRange f) (hmono : Monotone f) (x : α) :
∃ (u : ℕ → β), StrictAnti u ∧ (∀ (n : ℕ), f (u n) ∈ Set.Ioi x) ∧ Filter.Tendsto (f ∘ u) Filter.atTop (nhds x)
theorem eventually_le_const_iff_forall_gt_eventually_lt_const {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [FirstCountableTopology α] {l : Filter γ} [CountableInterFilter l] {f : γ → α} {a : α} :
(∀ᶠ (x : γ) in l, f x ≤ a) ↔ ∀ (b : α), a < b → ∀ᶠ (x : γ) in l, f x < b
theorem eventually_const_le_iff_forall_lt_eventually_const_lt {α : Type u_1} {γ : Type u_2} [TopologicalSpace α] [LinearOrder α] [OrderTopology α] [FirstCountableTopology α] {l : Filter γ} [CountableInterFilter l] {f : γ → α} {a : α} :
(∀ᶠ (x : γ) in l, a ≤ f x) ↔ ∀ b < a, ∀ᶠ (x : γ) in l, b < f x