Questions tagged [reproducing-kernel-hilbert-spaces]

A reproducing kernel Hilbert space (RKHS) is a Hilbert space of functions in which point evaluation is a continuous linear functional, which means that if two functions in the RKHS are close in norm, then they are also pointwise close.

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General approach to check if the given function is NOT a valid kernel

In general, for proving that the given kernel function is valid, I try one of the following two approaches: Check if the gram matrix is Symmetric Postive Semi Definite. Check if the kernel function can be expressed in terms of other functions by…
Ansh Khurana
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Reducing Kernel Hilbert Space: Reproducing property

If the inner product between two functions is the $\int f(x)g(x)dx$ and it's equal to $\int f(x)g(x)dx = f(x)$, what conditions must $g(x)$ satisfy in order for this equality to hold?
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How to prove that the Gram matrix of the Gaussian kernel has full rank?

I'm trying to prove that, given mutually different points $x_1,\dots,x_m$, the Gram matrix $G$ for the Gaussian kernel has $rank(G)=m$. If I can prove that the Gaussian kernel is strictly positive definite I could follow that all eigenvalues…
Conny
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RKHS of a Polynomial Kernel with negative roots

Wikipedia, and actually all books and ressources I could find, define a polynomlial kerenel as: $$ K: x,y \mapsto (x^Ty + c)^2, $$ where $c\ge 0$. What happens if $c < 0$? Take the following kernels for example: $$ \forall x,y \in…
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