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arXiv · 1110.4017

An extension of Mercer theorem to vector-valued measurable kernels

Ernesto De Vito·Veronica Umanita`·Silvia Villa
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Abstract

We extend the classical Mercer theorem to reproducing kernel Hilbert spaces whose elements are functions from a measurable space $X$into $\mathbb C^n$. Given a finite measure $μ$ on $X$, we represent the reproducing kernel $K$ as convergent series in terms of the eigenfunctions of a suitable compact operator depending on $K$ and $μ$. Our result holds under the mild assumption that $K$ is measurable and the associated Hilbert space is separable. Furthermore, we show that $X$ has a natural second countable topology with respect to which the eigenfunctions are continuous and the series representing $K$ uniformly converges to $K$ on any compact subsets of $X\times X$, provided that the support of $μ$ is $X$.

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Ernesto De Vito, Veronica Umanita`, Silvia Villa. 2011-10-18. An extension of Mercer theorem to vector-valued measurable kernels. https://arxiv.org/abs/1110.4017

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