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 : ) (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 : )  s  s  (t i.succ : )  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