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Spectral reciprocity and matrix representations of unbounded operators
Journal article   Open access   Peer reviewed

Spectral reciprocity and matrix representations of unbounded operators

Palle E.T Jorgensen and Erin P.J Pearse
Journal of functional analysis, Vol.261(3), pp.749-776
2011
DOI: 10.1016/j.jfa.2011.01.016
url
https://doi.org/10.1016/j.jfa.2011.01.016View
Published (Version of record) Open Access

Abstract

We study a family of unbounded Hermitian operators in Hilbert space which generalize the usual graph-theoretic discrete Laplacian. For an infinite discrete set X, we consider operators acting on Hilbert spaces of functions on X, and their representations as infinite matrices; the focus is on ℓ 2 ( X ) , and the energy space H E . In particular, we prove that these operators are always essentially self-adjoint on ℓ 2 ( X ) , but may fail to be essentially self-adjoint on H E . In the general case, we examine the von Neumann deficiency indices of these operators and explore their relevance in mathematical physics. Finally we study the spectra of the H E operators with the use of a new approximation scheme.
Graph Laplacian Reproducing kernel Unbounded linear operator Graph energy Electrical resistance network Discrete potential theory Tree Hilbert space Essentially self-adjoint Spectral graph theory

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