Is Locally Bounded of is Cadlag
isLocallyBounded_of_isCadlag
Plain-language statement
A càdlàg function is locally bounded.
Exact Lean statement
lemma isLocallyBounded_of_isCadlag {E : Type*} [LinearOrder ι] [PseudoMetricSpace E]
{f : ι → E} (hf : IsCadlag f) (x : ι) : ∃ t ∈ 𝓝 x, IsBounded (f '' t)Formal artifact
Lean source
lemma isLocallyBounded_of_isCadlag {E : Type*} [LinearOrder ι] [PseudoMetricSpace E] {f : ι → E} (hf : IsCadlag f) (x : ι) : ∃ t ∈ 𝓝 x, IsBounded (f '' t) := by obtain ⟨l, hl⟩ := hf.2 x obtain ⟨U, ⟨⟨A, ⟨hp, ⟨W, hW⟩⟩⟩, hU⟩⟩ := Metric.exists_isBounded_image_of_tendsto hl obtain ⟨V, ⟨⟨B, ⟨hq, ⟨R, hR⟩⟩⟩, hV⟩⟩ := Metric.exists_isBounded_image_of_tendsto (hf.1 x).tendsto refine ⟨A ∩ B, inter_mem hp hq, ?_⟩ apply IsBounded.subset ((hU.union hV).union (isBounded_singleton : Bornology.IsBounded ({f x}))) rintro _ ⟨y, ⟨hyL, hyR⟩ , rfl⟩ rcases lt_trichotomy y x with (hlt | heq | hgt) · have : y ∈ U := hW.2 ▸ ⟨hyL, hW.1 hlt⟩ grind · grind · have : y ∈ V := hR.2 ▸ ⟨hyR, hR.1 hgt⟩ grind- Project
- Brownian motion
- License
- Apache-2.0
- Commit
- 5077304f5e73
- Source
- BrownianMotion/StochasticIntegral/Cadlag.lean:192-205
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Related declarations
Continuous Within At Iio indicator Ioc
continuousWithinAt_Iio_indicator_Ioc
Plain-language statement
The indicator of a half-open interval Ioc a b with constant value c is left-continuous: when approached from the left it is eventually constant, so it is continuous within Iio t at t for every t.
Source project: Brownian motion
Person-level attribution pending.
Dense comap val nhds Within Iio ne Bot
Dense.comap_val_nhdsWithin_Iio_neBot
Plain-language statement
This is the dual of Dense.comap_val_nhdsWithin_Ioi_neBot.
Source project: Brownian motion
Person-level attribution pending.
Dense comap val nhds Within Ioi ne Bot
Dense.comap_val_nhdsWithin_Ioi_neBot
Project documentation
This is an auxillary lemma used to prove Dense.monotone_of_isRightContinuous. It is saying that if D is a dense set and a, b are two points such that a < b, then the comap of 𝓝[Set.Ioi a] a under the inclusion D → α is nontrivial. Note that a < b is necessary as this is clearly not true if a is a top element.
Source project: Brownian motion
Person-level attribution pending.