Recent content by Geometry

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    I How do charts on differentiable manifolds have derivatives without a metric?

    Math_QED : you can show it without Riemannian structure (in fact you can show the assertions above are equivalent to "##M## is homeomorph to a closed set of ##L^{2}(\mathbb{N})##").End of digression.
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    I How do charts on differentiable manifolds have derivatives without a metric?

    Hello, to answer to the first question, if you've got a topological space ##M## such that any ##x \in M## admit a neighborhood homeomorph to an open space of ##\mathbb{R}^{n}##, then the following assertion are equivalent : a)##M## is an Hausdorff space with a countable basis of open...
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    I Generalisation of Polarization identity

    Hello, This is very clear and very adapted for my needs. Thank you very much WWGD. I wish you a good day.
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    I Generalisation of Polarization identity

    Their is a a way to developed the formal sum : ##(x_1 + x_2 + ... + x_k)^n## no? It might help but this will create a big sum with a lot of binomial coefficient.
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    I Generalisation of Polarization identity

    Hello, If I have a quadratic form ##q## on a ##\mathbb{R}## vectorial space ##E##, its associated bilinear symmetric form ##b## can be deduce by the following formula : ##b(., .) = \frac{q(. + .) - q(.) - q(.)}{2}##. So that, an homogeneous polynomial of degree 2 can be associated to a blinear...
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    What is the Agrégation and How Does it Relate to Differential Geometry?

    Hello, thank you for your warming welcome. Have a nice day.
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    I Proof of ##F## is an orthogonal projection if and only if symmetric

    Hi, for the second equality you've got : ##||F(v)||^2 = <v, F(F(v))>## (because ##F## is symmetric) and this equate ##0## since ##v \in Im(F)^{\perp}## and ##F(F(v)) \in Im(F)##. Where is the problem? Perhaps I didn't understand the question.
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    What is the Agrégation and How Does it Relate to Differential Geometry?

    Hello, I'm new here. I'm french and I'm very interest at differential geometry. I came here to ask questions and if I can help other people. My level at school : I achieve (some years ago) a master degree and the agrégation (describtion here : https://en.wikipedia.org/wiki/Agr%C3%A9gation )...
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