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We adapt the well-known spectral decimation technique for computing spectra of Laplacians on certain symmetric self-similar sets to the case of magnetic Schrodinger operators and work through this method completely for the diamond lattice…

Classical Analysis and ODEs · Mathematics 2020-04-24 Antoni Brzoska , Aubrey Coffey , Madeline Rooney , Stephen Loew , Luke G. Rogers

We introduce self-similar versions of the one-dimensional almost Mathieu operators. Our definition is based on a class of self-similar Laplacians instead of the standard discrete Laplacian, and includes the classical almost Mathieu…

Spectral Theory · Mathematics 2022-05-18 Gamal Mograby , Radhakrishnan Balu , Kasso A. Okoudjou , Alexander Teplyaev

We study the subgroup structure, Hecke algebras, quasi-regular representations, and asymptotic properties of some fractal groups of branch type. We introduce parabolic subgroups, show that they are weakly maximal, and that the corresponding…

Group Theory · Mathematics 2009-11-27 Laurent Bartholdi , Rostislav I. Grigorchuk

We study the spectral theory of a class of piecewise centrosymmetric Jacobi operators defined on an associated family of substitution graphs. Given a finite centrosymmetric matrix viewed as a weight matrix on a finite directed path graph…

Spectral Theory · Mathematics 2022-01-19 Gamal Mograby , Radhakrishnan Balu , Kasso A. Okoudjou , Alexander Teplyaev

We show that certain representations of graphs by operators on Hilbert space have uses in signal processing and in symbolic dynamics. Our main result is that graphs built on automata have fractal characteristics. We make this precise with…

Operator Algebras · Mathematics 2008-03-14 Ilwoo Cho , Palle E. T. Jorgensen

We define the independence ratio and the chromatic number for bounded, self-adjoint operators on an L^2-space by extending the definitions for the adjacency matrix of finite graphs. In analogy to the Hoffman bounds for finite graphs, we…

Functional Analysis · Mathematics 2014-10-07 Christine Bachoc , Evan DeCorte , Fernando Mario de Oliveira Filho , Frank Vallentin

The method of spectral decimation is applied to an infinite collection of self--similar fractals. The sets considered belong to the class of nested fractals, and are thus very symmetric. An explicit construction is given to obtain formulas…

Analysis of PDEs · Mathematics 2018-08-27 Sergio A. Hernandez , Federico Menendez-Conde

Laplacian operators on finite compact metric graphs are considered under the assumption that matching conditions at graph vertices are of $\delta$ and $\delta'$ types. An infinite series of trace formulae is obtained which link together two…

Spectral Theory · Mathematics 2014-11-06 Yulia Ershova , Irina I. Karpenko , Alexander V. Kiselev

This paper explores a previously uncharted automaton group generated by a 5-state automaton $(\Pi, A)$ acts by self-similarity on the regular rooted tree $A^{*}$ over a 2-letter alphabet set $A$. Group $G$ has been subjected to several…

Group Theory · Mathematics 2023-10-26 Bozorgmehr Vaziri , Frahad Rahmati

We study spectra of noncommutative dynamical systems, representations of fractal groups, and regular graphs. We explicitly compute these spectra for five examples of groups acting on rooted trees, and in three cases obtain totally…

Group Theory · Mathematics 2009-11-28 Laurent Bartholdi , Rostislav I. Grigorchuk

We show a norm convergence result for the Laplacian on a class of post-critically finite fractals with arbitrary Borel regular probability measure which can be approximated by a sequence of finite-dimensional graph Laplacians with…

Spectral Theory · Mathematics 2018-09-10 Olaf Post , Jan Simmer

On finite metric graphs we consider Laplace operators, subject to various classes of non-self-adjoint boundary conditions imposed at graph vertices. We investigate spectral properties, existence of a Riesz basis of projectors and similarity…

Spectral Theory · Mathematics 2021-03-30 Amru Hussein , David Krejcirik , Petr Siegl

Motivated by potential theory on discrete spaces, we study a family of unbounded Hermitian operators in Hilbert space which generalize the usual graph-theoretic discrete Laplacian. These operators are discrete analogues of the classical…

Functional Analysis · Mathematics 2011-02-01 Palle E. T. Jorgensen , Erin P. J. Pearse

There is a recently discovered connection between the spectral theory of Schr\"o-dinger operators whose potentials exhibit aperiodic order and that of Laplacians associated with actions of groups on regular rooted trees, as Grigorchuk's…

Group Theory · Mathematics 2016-07-01 Rostislav Grigorchuk , Daniel Lenz , Tatiana Nagnibeda

Combining the study of the simple random walk on graphs, generating functions (especially Green functions), complex dynamics and general complex analysis we introduce a new method of spectral analysis on self-similar graphs. We give an…

Combinatorics · Mathematics 2007-05-23 Bernhard Krön

We establish a spectral duality for certain unbounded operators in Hilbert space. The class of operators includes discrete graph Laplacians arising from infinite weighted graphs. The problem in this context is to establish a practical…

Functional Analysis · Mathematics 2008-08-05 Dorin Ervin Dutkay , Palle E. T. Jorgensen

We study operators on rooted graphs with a certain spherical homogeneity. These graphs are called path commuting and allow for a decomposition of the adjacency matrix and the Laplacian into a direct sum of Jacobi matrices which reflect the…

Spectral Theory · Mathematics 2012-01-04 Jonathan Breuer , Matthias Keller

This paper is a survey, with few proofs, of ideas and notions related to self-similarity of groups, semi-groups and their actions. It attempts to relate these concepts to more familiar ones, such as fractals, self-similar sets, and…

Group Theory · Mathematics 2009-11-29 Laurent Bartholdi , Rostislav I. Grigorchuk , Volodymyr V. Nekrashevych

We introduce a family of post-critically finite fractal trees indexed by the number of branches they possess. Then we produce a Laplacian operator on graph approximations to these fractals and use spectral decimation to describe the…

Classical Analysis and ODEs · Mathematics 2011-05-11 Daniel Ford , Benjamin Steinhurst

In this paper, we study the asymptotic behavior of the traces of Hecke operators for spherical discrete automorphic representations of fixed level on general split reductive groups over $\mathbb{Q}$. Under a condition on the analytic…

Number Theory · Mathematics 2019-09-20 Tobias Finis , Jasmin Matz
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