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Calabi
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Hello : CONTEXT : let be E the space of rapidly decreasing functions on
##\mathbb{R}^{n}## in ##\mathbb{R}##.
I define
$$(||.||_{i})_{i \in \mathbb{R}^{n+1}}$$ with forall ##i = (k, m_{1},\ldots, m_{n}) = (k, m)## we define for ##f## in ##E## ##||f||_{i} = \sup_{x \in \mathbb{R}^{n}} \Big|(1 + ||x||^{k}) \frac{\partial^{m}f}{\partial x_{1}^{m_{1}}\ldots \partial x_{n}^{m_{n}}}(x)\Big|##.
They are seminorm. Let wright this family of semi norm as ##(||.||_{n})_{n ×\in \mathbb{N}}##.
My goal is to show that the topologie associate to the family of semi norm is not normable.
What I do for the moment : I've define a distance on E with ##\forall (x, y) \in E^{2} d(x, y) = \sum_{n \in \mathbb{N}}2^{-n}min(1, ||x - y||_{n})##. It define the same topology(not rally complicate.). I also prevously show that for all ##\epsilon < 1##, ##\{B(0, \frac{\epsilon}{n +1} / n \in \mathbb{N}\}## is a base of neighbourhood of 0. We advice me to use that.
Wich is denombrable. But I find nothing else on.Then I'll try to show an absurdity : by using Riesz theorem by showing E is finite dimension by showing the unity sphere is compacts. I try to use my distance.
I find nothing.
Could you help me pelase?
Thank you in advance and have a nice afternoon.
##\mathbb{R}^{n}## in ##\mathbb{R}##.
I define
$$(||.||_{i})_{i \in \mathbb{R}^{n+1}}$$ with forall ##i = (k, m_{1},\ldots, m_{n}) = (k, m)## we define for ##f## in ##E## ##||f||_{i} = \sup_{x \in \mathbb{R}^{n}} \Big|(1 + ||x||^{k}) \frac{\partial^{m}f}{\partial x_{1}^{m_{1}}\ldots \partial x_{n}^{m_{n}}}(x)\Big|##.
They are seminorm. Let wright this family of semi norm as ##(||.||_{n})_{n ×\in \mathbb{N}}##.
My goal is to show that the topologie associate to the family of semi norm is not normable.
What I do for the moment : I've define a distance on E with ##\forall (x, y) \in E^{2} d(x, y) = \sum_{n \in \mathbb{N}}2^{-n}min(1, ||x - y||_{n})##. It define the same topology(not rally complicate.). I also prevously show that for all ##\epsilon < 1##, ##\{B(0, \frac{\epsilon}{n +1} / n \in \mathbb{N}\}## is a base of neighbourhood of 0. We advice me to use that.
Wich is denombrable. But I find nothing else on.Then I'll try to show an absurdity : by using Riesz theorem by showing E is finite dimension by showing the unity sphere is compacts. I try to use my distance.
I find nothing.
Could you help me pelase?
Thank you in advance and have a nice afternoon.
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