Zulip Chat Archive

Stream: Is there code for X?

Topic: Limit of addition of functions


Ashvni Narayanan (Jul 05 2022 at 16:02):

I am looking for a lemma of the form :

example {X : Type*} [topological_space X] [t2_space X] [add_comm_monoid X] [has_continuous_add X]
  (f g :   X) : lim filter.at_top (λ x : , f x + g x) = lim filter.at_top (λ x : , f x) + lim filter.at_top (λ x : , g x) := sorry

Any help is appreciated. Thank you!

Sebastien Gouezel (Jul 05 2022 at 16:05):

Have a look at docs#filter.tendsto.add

Sebastien Gouezel (Jul 05 2022 at 16:06):

The lemma as you wrote it can not be true (what happens if one function is not converging?). In general, don't use lim, and use tendsto instead.

Ashvni Narayanan (Jul 05 2022 at 16:08):

Sebastien Gouezel said:

The lemma as you wrote it can not be true (what happens if one function is not converging?). In general, don't use lim, and use tendsto instead.

Thank you! I know this is not true in general, I was looking for a better lemma that has probably already formulated it.


Last updated: Dec 20 2023 at 11:08 UTC