Positive definiteness‎, ‎reproducing kernel Hilbert spaces and beyond

Positive Definiteness, Reproducing Kernel Hilbert Spaces and Beyond

Positive definiteness, reproducing kernel Hilbert spaces, integral operators and Mercer’s theorem in its various formats are common topics in many branches of mathematics. In this paper we review and upgrade upon some recent results that always involve at least two of them and indicate a few directions in which additional research could be carried out.

Real reproducing kernel Hilbert spaces

P (α) = C(α, F (x, y)) = αF (x, x) + 2αF (x, y) + F (x, y)F (y, y), which is ≥ 0. In the case F (x, x) = 0, the fact that P ≥ 0 implies that F (x, y) = 0. In the case F (x, y) 6= 0, P (α) is a quadratic polynomial and because P ≥ 0 it follows that the discriminant of P is ≤ 0: 4F (x, y) − 4 · F (x, x) · F (x, y)F (y, y) ≤ 0. That is, F (x, y) ≤ F (x, y)F (x, x)F (y, y), and this implies that F ...

Some Properties of Reproducing Kernel Banach and Hilbert Spaces

This paper is devoted to the study of reproducing kernel Hilbert spaces. We focus on multipliers of reproducing kernel Banach and Hilbert spaces. In particular, we try to extend this concept and prove some related theorems. Moreover, we focus on reproducing kernels in vector-valued reproducing kernel Hilbert spaces. In particular, we extend reproducing kernels to relative reproducing kernels an...

Reproducing kernel Hilbert spaces and Mercer theorem

We characterize the reproducing kernel Hilbert spaces whose elements are p-integrable functions in terms of the boundedness of the integral operator whose kernel is the reproducing kernel. Moreover, for p = 2 we show that the spectral decomposition of this integral operator gives a complete description of the reproducing kernel.

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