Zulip Chat Archive
Stream: Is there code for X?
Topic: Lebesgue number lemma for paths?
Kim Morrison (Nov 10 2025 at 06:11):
Does anyone have:
import Mathlib
theorem Path.exists_partition_in_cover {X : Type*} [TopologicalSpace X]
{ι : Type*} (U : ι → Set X) (hU_open : ∀ i, IsOpen (U i))
{x y : X} (γ : Path x y) (hU_cover : Set.range γ ⊆ ⋃ i, U i) :
∃ (n : ℕ) (t : Fin (n + 1) → unitInterval),
StrictMono t ∧ t 0 = 0 ∧ t (Fin.last n) = 1 ∧
(∀ i : Fin n, ∃ j : ι,
∀ s : unitInterval, (t i.castSucc : ℝ) ≤ s ∧ s ≤ (t i.succ : ℝ) → γ s ∈ U j) := by
sorry
Joël Riou (Nov 10 2025 at 06:19):
Just in case, it should follow easily from docs#lebesgue_number_lemma_of_metric
Kim Morrison (Nov 10 2025 at 06:37):
Ah, just found docs#exists_monotone_Icc_subset_open_cover_unitInterval
Kim Morrison (Nov 10 2025 at 06:42):
Slight impedance mismatch with Nat/Fin and Monotone/StrictMono, I might just provide variants.
Last updated: Dec 20 2025 at 21:32 UTC