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Feb 8, 2020 at 11:39 history edited YCor
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Feb 7, 2020 at 17:01 history edited YCor CC BY-SA 4.0
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Aug 13, 2014 at 12:17 history edited user144542 CC BY-SA 3.0
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May 8, 2014 at 12:23 vote accept user144542
May 8, 2014 at 9:50 answer added gsa timeline score: 3
May 8, 2014 at 7:22 comment added András Bátkai My first comment was on the semigroup case, where you can have many weird things happening. For bounded $A$ you can modify the finite dimensional case. I will return to your question of the $C_0$-group case soon.
May 8, 2014 at 0:26 comment added user144542 @Andr My problem is I want a $C_0$ group $T(t)$ or a function $e^{tA}$ and a vector $x \in X$ such that $T(t)x$ is bounded on $\mathbb{R}$, nontrivial and $\inf_{t \in \mathbb{R} }|T(t)x|=0$. It seems like I cannot modify the nilpotent translation semigroup you gave to make it a group. I am interest in the solutions on the whole real line, since $\inf_{t \geq 0 }|T(t)x|=0$ is of course simply verified by exponentially stable orbits. Thanks !
May 7, 2014 at 19:07 comment added András Bátkai The two answers to this question: mathoverflow.net/q/164182/12898 will give you full and detailed answer.
May 7, 2014 at 18:34 comment added Loïc Teyssier Have you tried to reproduce the proof for finite dimesional spaces in the case of a general Banach space ? The arguments may differ but you should either be able to adapt it or to pinpoint crucial steps that may help you find a counter-example.
May 7, 2014 at 15:49 review First posts
May 7, 2014 at 15:54
May 7, 2014 at 15:46 comment added Christian Remling The question is not really meaningful for a semigroup when you can only consider $t\ge 0$, and of course $\inf_{t\ge 0} \|x(t)\|=0$ wouldn't be unexpected.
May 7, 2014 at 15:33 history asked user144542 CC BY-SA 3.0