Zulip Chat Archive
Stream: Is there code for X?
Topic: Almost sure limits are almost surely unique
Peter Pfaffelhuber (Jun 21 2024 at 22:19):
If almost surely, and almost surely (wrt some measure), then almost surely. This basic fact must be in Mathlib, I guess, but I cannot find it. Or does it follow from some more general filter results?
The implementation is not hard, but I want to learn how this is implemented in mathlib:
example {α ι E : Type*} [TopologicalSpace E] [T2Space E] {x : MeasurableSpace α} {μ : Measure α} {Y Z : α → E} {X : ι → α → E} {l : Filter ι} [l.NeBot]
(hY : ∀ᵐ ω ∂μ, Filter.Tendsto (fun i => X i ω) l (nhds (Y ω))) (hZ
: ∀ᵐ ω ∂μ, Filter.Tendsto (fun i => X i ω) l (nhds (Z ω))) : Y =ᵐ[μ] Z := by
filter_upwards [hY, hZ] with ω hY1 hZ1
exact tendsto_nhds_unique hY1 hZ1
Kevin Buzzard (Jun 22 2024 at 00:33):
Nice proof! Could try loogling for theorems whose conclusion is that two things are almost surely equal if you're wondering if it's there already?
Yury G. Kudryashov (Aug 13 2024 at 22:18):
As you can see from the proof, it works for any filter.
Yury G. Kudryashov (Aug 13 2024 at 22:19):
@loogle Filter.Tendsto, T2Space, |- Filter.EventuallyEq _ _ _
loogle (Aug 13 2024 at 22:19):
:shrug: nothing found
Yury G. Kudryashov (Aug 13 2024 at 22:19):
Probably, it's not there.
Last updated: May 02 2025 at 03:31 UTC