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Jul 23, 2018 at 1:30 comment added Check drummer To Mateusz: but $|x_1−y_1|≤|x_0−y_0|$ is not genrally true,
Jul 21, 2018 at 14:26 comment added Mateusz Kwaśnicki Choose $x_0 \ne y_0$, and let $x_{n+1} = f(x_n)$ and $y_{n+1} = f(y_n)$. Next, choose a convergent subsequence $(x_{k_n},y_{k_n})$, and set $l_n=k_{n+1}-k_n$. Since $|x_0-x_{l_n}| \le |x_{k_n}-x_{k_{n+1}}|$, $(x_{l_n})$ converges to $x_0$. Similarly, $y_{l_n}$ converges to $y_0$. Therefore, $|x_{l_n}-y_{l_n}| \to |x_0 - y_0|$. On the other hand, $|x_{l_n}-y_{l_n}|\ge|x_1-y_1|$, so $|f(x_0)-f(y_0)| = |x_1-y_1|\le|x_0-y_0|$, a contradiction. See here.
Jul 21, 2018 at 9:35 comment added Alec Rhea It's possible for a moderator to move it and that would preserve the rep boost I believe, but probably faster to copy then delete it yourself and repost. No problem.
Jul 20, 2018 at 23:23 comment added Check drummer Can it be moved automatically or can I do it somehow? Thank you
Jul 18, 2018 at 22:20 history closed David Roberts
Emil Jeřábek
Wolfgang
Nik Weaver
Yemon Choi
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Jul 18, 2018 at 10:48 history edited Andrés E. Caicedo
edited tags
S Jul 18, 2018 at 7:41 history suggested Amir Sagiv CC BY-SA 4.0
English and Tex
Jul 18, 2018 at 6:59 review Suggested edits
S Jul 18, 2018 at 7:41
Jul 18, 2018 at 6:33 review Close votes
Jul 18, 2018 at 22:24
Jul 18, 2018 at 5:58 comment added Alec Rhea This should be moved over to/deleted and re-asked at math.stackexchange.
Jul 18, 2018 at 5:56 review First posts
Jul 18, 2018 at 6:59
Jul 18, 2018 at 5:56 history asked Check drummer CC BY-SA 4.0