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5h
awarded  Notable Question
Mar
19
awarded  Popular Question
Feb
13
awarded  Popular Question
Oct
21
awarded  Popular Question
Jul
18
accepted Distortion and Norm Stabilization
Jul
18
comment Distortion and Norm Stabilization
Nice answer! The "trick" I did not see was your first inequality; everything follows from it. I think that it is important to note that when you prove that the existence of a distortable subspace $Y$ gives you a non-stabilizing equivalent norm $\lvert \cdot \rvert$, we are implicity using the fact that we can extend $\lvert \cdot \rvert$ from $Y$ to an equivalent norm on $X$ (since, by definition, we need this norm to be defined on the whole space, not just on $Y$).
Jul
17
revised Distortion and Norm Stabilization
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Jul
17
revised Distortion and Norm Stabilization
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Jul
17
comment Distortion and Norm Stabilization
@ChristopherA.Wong: We say that $X$ is distortable if it is $\lambda$-distortable for some $\lambda > 1$.
Jul
17
revised Distortion and Norm Stabilization
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Jul
17
asked Distortion and Norm Stabilization
Jul
2
awarded  Curious
Jun
5
accepted Correlation Sequences and Unitary Operators
Jun
5
comment Correlation Sequences and Unitary Operators
It came up during a lecture on Fourier Analysis, right before proving Wiener Theorem. I guess it was supposed to be "trivial".
Jun
5
comment Correlation Sequences and Unitary Operators
Never mind, I understand it now.
Jun
4
comment Correlation Sequences and Unitary Operators
How do you know that Wiener's Theorem implies $\frac1N\sum_{n=1}^N|c_n|^2\xrightarrow[N\to\infty]{}0$? I mean, it seems that you're assuming that $\mu$ is continuous.
Jun
4
revised Correlation Sequences and Unitary Operators
edited title
Jun
4
revised Correlation Sequences and Unitary Operators
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Jun
3
comment Correlation Sequences and Unitary Operators
Is really close. However, my question is about convergence in $\mathbb{R}$, not in $H$ (as in the Mean Ergodic Theorem). I still don't see how to approach this problem...
Jun
3
revised Correlation Sequences and Unitary Operators
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