Zulip Chat Archive

Stream: Is there code for X?

Topic: uniform convergence on a compact set


Floris van Doorn (Oct 15 2021 at 15:21):

Do we already have the following?
On a compact set, to show that a sequence of functions convergences uniformly (docs#tendsto_uniformly) it is sufficient to show that it converges pointwise.
The closest statement I can find is Heine-Cantor docs#is_compact.uniform_continuous_on_of_continuous
(@Patrick Massot)

Sebastien Gouezel (Oct 15 2021 at 16:13):

I am not sure I understand your statement. Consider the function f_n from [0, 1] to \R, which is equal to 0 at 0 and on [2/n, 1], to 1 at 1/n and affine inbetween. It converges pointwise to 0, but not uniformly.

Floris van Doorn (Oct 15 2021 at 19:08):

Ah, thanks for the counterexample. What I was thinking of was indeed false. I also think I figured out that in my actual application I can just use Heine-Cantor, so there's nothing to see here. Thanks for the answer!


Last updated: Dec 20 2023 at 11:08 UTC